old sweat

plural old sweats · alternative old-sweat

1. UKWorld War IslanggovernmentAn experienced soldier.
2. UKslanggovernmentA veteran soldier or war veteran.

   1 more example

   A lifelong buddy of mine, this Herring, linked to me by what are called imperishable memories. Years ago, when striplings, he and I had done a stretch together at Malvern House, Bramley-on-Sea, the preparatory school conducted by that prince of stinkers, Aubrey Upjohn MA, and had frequently stood side by side in the Upjohn study awaiting the receipt of six of the juiciest from a cane of the type that biteth like a serpent and stingeth like an adder, as the fellow said. So we were, you might say, rather like a couple of old sweats who had fought shoulder to shoulder on Crispin's Day, if I've got the name right.

   1960, P. G. Wodehouse, chapter I, in Jeeves in the Offing

3. UKfigurativelyslangSomeone experienced in his or her field.