A contracted word used to correct people who improperly use the word "dethaw" to really mean "thaw". Dethaw isn't a word at all, the word thaw stands alone to mean "bring something to room
temperature". However, some people use the word dethaw, which would literally mean to take something out of the freezer and throw it right back in. Undethaw is used to correct them by use of a
double negative. Also, if they are really screwed up, they will come back at you with reundethaw, which of course means
the damn thing stays frozen.