..........on that Windermere (not truly a mere, though).
A while ago I compiled a list of place name derivations in the Lake District, mostly based on a book by Robert Gambles.
Windermere = Old Norse Vinandar + Old English Mere. Vinandar is the genitive form of the O.N. personal name Vinandr, hence Vinandr's lake.
It was recorded in c. 1180 as Wynandrmer.
O.E. mere = sea or lake, related to Old Saxon meri, Old Norse marr, Old High German mari. Compare Latin mare. (source dictionary.reference.com)
........... a body of water whose breadth is much greater than its depth..........
Well done, you!That's merely a pond.