I have to agree with this suggestion - both 'calve' (verb) and 'calves' (noun plural) should count (imho).
Interestingly in the game in question - (volcanoes) - both 'loave' and 'loaves' were accepted, the former as rare. A similar pair of words to 'calve' and 'calves'.
I've no idea what 'loave' means, (perhaps one of the other 40 who played it knows), but, intending to play 'loaves' I hit the submit key too soon and this (to me) unknown word was accepted.
MK