Old English wealwian "to roll," from West Germanic *walwon, from PIE root *wel- (3) "to roll" (see volvox). Figurative sense of "to plunge and remain in some state or conditio [..]

(n) an indolent or clumsy rolling about(v) devote oneself entirely to something; indulge in to an immoderate degree, usually with pleasure(v) roll around,(n) a puddle where animals go to wallow(v) ris [..]

When the rear end feels loose or wanders.  Normally caused by too much rebound.

To lie in the trough of a sea and roll heavily; to roll under the sea.

(intransitive) To roll oneself about in something dirty, for example in mud (Pigs wallow in the mud.) * Shakespeare: *: I may wallow in the lily beds. to move lazily or heavily in any medium; [..]