How old is English?
I urge all people who (after asking Google or another search robot) land onto this page to read first the summary of this website. I can't repeat myself all the time..
 Let it be clear: a 'pre-Celtic language' means: we-don't-know. It's scientific rubbish. The only
'pre-Celtic' language to be found in Europe is Basque. Besides, Basque is not pre-Celtic but pre-agricultural. All
other European languages (except Hungarian and Finnish which are related to Siberian/Uralic languages) are derived from the
Proto-Indo-European (PIE) language. If you read the summary, then you'll know that 'Celtic' didn't exist as a specific
language. click here for more
The etymology of Mersey is thought to be 'border river' from the Old English way of writing
Maere's-ea, where maere is northwest dialect for 'mark' (border-pole) and ea is simply PIE for Water. A
monk wrote in Old English: "Mersey means mark's-water (border river)" so referring to the fact that the
river had just then been chosen to become the political border between the kingdoms of Northumbria and Mercia.
 The Roman writer Tacitus mentioned both. The medieval name was Temese.
The Thames is also called 'Isis' in Oxford (and upstream). Some people argue that the 'Thames' is the
contraction of 'Tame', a left tributary of the Thames, and 'Isis' (Tame+isis =Tamisis). Most etymologists consider this
explanation as a fairy tale. What could be is that 'isis' used to be 'Isas' which could be the plural of 'Isa'. . The
etymology of Paris (from the tribe Parisii) is explained as 'par isa' = 'close to the river' or 'people
living on the river shores' (compare : ancient Greek 'para' = close to. 'Para' is a cognate to our word 'for'.
 We find exactly the same in modern Dutch:
Thames & London
The Thames has a wide estuary
Some British etymologists believe that the word Thames is pre-Celtic.  That is because no convincing 'Celtic' etymology could be found. Some will disagree and state the Thames means "the dark one", derived from the Brythonic word 'tam' = dark. But a number of counterarguments exist. To start with, linguistically it is inconsistent. And how dark was the water of the Thames? In Roman times, its water must have been clear, pure and full of fish.
There is also this strange coincidence that the place-name 'London' can likewise not be explained satisfactorily in Brythonic.
In the Middle Ages, the Thames was called "the London river" by sailors. Simple coincidence? Anyway, it is weird that London and its Thames obviously existed before the Romans came, and yet, no decent Brythonic etymology was ever found for this alleged 'very Celtic' city.
Richard Coates, one of Britain's best known etymologists, needs several pages to explain the etymology of 'London' and even then his explanation remains unsatisfactory for it feels too far-fetched, too artificial. Coates proposes a pre-Celtic word *Plowonida meaning 'boat river' or something similar.
But, rest assured, Thames has a far less problematic etymology and so does London, we found that in proto-Germanic. What say you? London was never portrayed as 'Celtic' let alone 'very Celtic' by contemporaries.
Thames = te + em + isa. In Latin : Tamesa or Tamesis.
On the Continent there are rivers called Eem (Holland), Amstel (A dam was build
near the Amstel and the place is now called Amsterdam). The Eems (Dutch version) or Ems (German
version) forms the border northeast Holland with Germany. Note that the ancient name for the Ems was Amesis. An
Emme flows in Switzerland, compare: Emmenthal cheese.
The Amstel, the Eems, Eem and the Thames have in common their sudden widening of the river, their estuaries,
where the river leads to or has a basin, a wide body of water.
The original river name was Ems or Ams : 'river-with-large-estuary'. The notion 'thames' (temse) referred to a specific spot along the river, namely the riverbanks in the London area (aT+Ems/Ames), as well as to the adjacent section of the river. The 's' at the end is 'isa', akin to the German river Weser.
The name Weser parallels the names of other rivers such as the Wear in England and the Vistula in Poland, all of which are ultimately derived from the root *weis- "to flow", which gave Old English/Old Frisian wase "mud, ooze", Old Norse veisa "slime, stagnant pool", Dutch waas "lawn", Old Saxon waso "wet ground, mire", and Old High German wasal "rain". (Wikipedia)The Germanic languages have a odd habit to drop a leading 'w' in some words. The English word 'wool' is 'ull' in Swedish, 'wolf' is 'ulf' and 'word' is 'ord'. So, 'Weser' can have its 'w' dropped and becomes 'Eser', or 'Yser' (Belgium/West Flanders) or Isère (France/southeastern Alps) or Isar (Austria, Vienna), etc. [see right: Isis]. So, Temese referred in the centuries BC to a special place on the riverbank, NOT to the (whole) river itself.
Typical for natural estuaries is that their banks are regularly flooded, especially at spring tide. The height of this tide is difficult to predict as it can be combined with a northerly wind and storm. Building a house close to the water is hazardous under these conditions. So people searched for a settling place that was at the same time close enough and safe enough. This place is found more upstream. At a certain point, floods are reduced to a minimum. This place on the Thames river banks is the region of London. That river section was during the Bronze Age called 'Temse' or 'where the estuary (and its floods) begins'. The Ravenna Cosmography (see below) mentions TAMESE as a place, for it never mentions rivers.
Compound place names remained common in Old English according to the Oxford English Dictionary (OED). The Romans wrote down the words as they were: compound words. An example is Dubris (Dover) : *duo (two) + *ofer (riverbank, shore). Compare with Dutch oever ; German Ufer = shore, riverbank. Notice that *ofer is a word only found in the Germanic languages. Thus Dover = double shore or spit. (more)
As more houses were build there, the place along the river became known as 'Lands (e)t Ames' (in modern English - see lower: London). The location became the most important point where the river could be crossed by ferry. Travellers eventually called the river itself 'Temse' and kept 'Lands' (in modern English) or (in Old-English) 'Landen/Londen' for the village.
When the Romans settled, the word Tamese was already used for the river itself.
The 'h' in Thames is a late affectation, the name is to be pronounced 'Tems'.
There is a city in Flanders, Belgium, located upon the river Schelde, that has the name Temse. In
French: Tamise. There the river suddenly widened in ancient times, that is, before the river was captured (later) between
dykes. The specific location of Temse on the river corresponds perfectly with that of London: where the estuary began.
There is a Temse in Germany, a short natural channel between the river Warnow and the Butzower lake (village of Butzow, Mecklenburg, north-east Germany). Here also it refers to a 'wide water body' (lake).Etymology of Thames: 'aT (the) ames' = 'inhabited place where the estuary begins'. The Romans wrote: Tamisa or Tamesa.  The river would later (before the Romans came!) be named similar to 'the London river' as 'the Thames river'.
There is a remarkable similarity with the river name 'Humber'. In the first part we recognize the same 'ham'. The last part ('ber') means 'brown'. The animal 'bear' is also thought to mean 'the brown one'. A visit to the Humber will convince anyone of its brown colour. So, Humber = brown ham, wide brown water. A clear Germanic word.
As the word Thames shifted in meaning from the banks of the river to the river itself, the word 'lands' on the shore gradually replaced it. This could have happen after the 8th century BC. See next :
Nobody seems to know where the name London comes from. There is officially no etymological explanation
for the Latin name Londinium. What is certain is that it was not the place of Mr. Londin. All names, including
family names, had a meaning, and clearly 'Londin' means nothing, it's just a displacement of the problem. An alternative
explanation is simple: Landen, if one accepts that the place-name was originally proto-English. 'Land-en' (aphonic
'e') is an ancient English, but still used in Dutch, plural for 'land'.
The explanation would be perfect for the place where London is and quite logical. London must have been
called Landen before the Romans came. Probably as a small settlement just before the widening delta of the Thames. A boat
brought passengers to the other side of the river. The Romans must have found the location excellent and made a 'big' city of
the former village (with a staggering 4000 inhabitants at its peak). For more about that figure, click
here. The Roman bridge across the Thames provided the only way to travel north-south without getting into a boat in
eastern Britain. The Romans latinised Londen into Londin and added '-ium' for declension purposes (for land <> lond ,
Place-names like Landen or with -land occur also in the other Germanic regions. The place-name 'Landen' replaced the earlier place-name 'Tems'.
This explains also the French version: Londres. 'Landen' with '-en' plural was not the only possibility. A more High German '-er' ('Lander') could also be used. In middle Dutch there was some sort of competition between '-en' plural and '-er'. Eventually '-en' would prevail in Dutch. There was a similar plural battle in England: child -> childer -> childeren (children). Some regions used more '-en' and some more '-er' plurals. Later, '-en' became standard (probably in the southeast) and people forgot that '-er' was already a plural . The '-en' plural won the game, just before it was replaced by the now common (and French) '-s' plural. The French understood it was a plural, but must have obtained the name from '-er' users. So they added their own plural '-s' and pronounced it Londers or (today) Londres.
The Ravenna cosmography (700 AD - Vatican codex) refers to TAMESE as a place, not a river, just after
LANDINI. However, Londinium Augusti is also mentioned. The Romans used a place-names list if they wanted to travel
from one place to another. One could buy such a list. The Ravenna cosmography is thought to be a copy of a copy of a copy....
of several such lists which themselves were compiled to obtain a worldwide (from Ireland to India) road book. This adding up
method is confusing and far from precise. The compiling monk had no idea and had probably never left his native Ravenna.
Around 1450 AD, English became an official language in Parliament (it had been French between 1215 and 1450)
and as a consequence the Chancellery at Westminster decided to regularize the English spelling as a common written language
was needed. Among the many words which received a single written version was the word 'lond' which became 'land',
although this took a long time to settle ("The Adventure of English", Melvyn Bragg, 2003, page 98). Clearly, a
significant proportion of the English still used 'lond' instead of the modern 'land'.
Therefore, London means 'the houses', as people originally (a few centuries BC!) referred to the few houses
owned by fishermen, ferryboat men, helpers, merchants and some artisans (carpenters, smiths, etc) et al. These
'houses' were situated where the estuary began, at the time the most sensible place: the Tems-place. The full place-name
would have been: "the houses at the Ems". Centuries later some people would continue to say 'Temse', not referring
to the river but to that specific inhabited place just before the estuary and dropping the obvious 'houses' (=lands) word as
has been suggested for a thorp . But most others split both notions and one part became applicable for the whole
length of the 'London river' and the other part became a sort of stand alone place-name which apparently just happened to be
split by the river.
Note that the words land or lond (Londinium), tems (Tamisa) are words belonging to the Germanic
language group. They do not occur in Brythonic (wrongly called 'Celtic'), nor in any other European language group. They were
written down by the Romans long before the Anglo-Saxons set foot in Britain. Read the summary for
more information about that.