undertoad noun2 •An underlying threat of disaster beneath the surface of everyday life.You're like Garp; you always imagine every terrible thing that could possibly happen. You see undertoads everywhere. — 1994 •A mythical monster that lurks underwater to catch unwary swimmers; a personification of an undertow.It was that undertoad what took old Bill's boy clean under the water and never brung him back up,” reminisced Will. — 2004 formsundertoads