The name Cermië (or its Sindarin equivalent Cerveth) are not explained, and nor are there any known Elvish roots that fit well enough to be sure of the name's meaning. Circumstantially, though, there seems to be a connection with the root meaning 'cut'. In combination with the fact that Cermië was a late summer month, an interpretation of something like 'harvest' (or possibly the 'cutting' of hay, given that Cermië was earlier than most other 'harvest' months) seems more than plausible.