v. & n.
v. (wagged, wagging) 1 tr. & intr. shake or wave rapidly or energetically to and fro. 2 intr. archaic (of the world, times, etc.) go along with varied fortune or characteristics.
n. a single wagging motion (with a wag of his tail). the tail wags the dog the less or least important member of a society, section of a party, or part of a structure has control. tongues (or beards or chins or jaws) wag there is talk.
[ ME waggen f. root of OE wagian sway ]