There are two possible explanations: first, a small pond must have already existed before the land was given to the monks and have already called ''Mortemer'' like the two other ''Mortemer'', because the word ''mer'' 'pond' was not used anymore beyond the Xth century. This word is only attested in North-Western France and of Frankish or Saxon origin ''mari / meri'' 'mere', 'lake' (in Cambremer, Blingemer, etc..); ''mort(e)'' 'dead' is also quite common to mean 'stagnant' (in Port-Mort 'the port with stagnant water', Morteau 'dead water', etc.).〔François de Beaurepaire, ''Les noms des communes et anciennes paroisses de la Seine-Maritime'', éditions Picard 1979. ISBN 2-7084-0040-1.〕 Second, the monks could have given the name ''Mortemer'' to their drainage lake to remember the other Mortemer for any kind of reason we don't know, making a pun at the same time with ''Mer Morte'' 'Dead Sea'.