I am reading the diary of a Colonel in the British Army in the 1940s. He describes some of the recruits as "old stiffs".
This seems to be largely a compliment, and seems to refer to older folk who have fought in earlier conflicts.
I would appreciate a more subtle description of an "old stiff", though.
(I am a native speaker, so know a fair few meanings of the word, and have looked through a couple of dictionaries for additional meanings, and none seem quite to fit, or else it is hard to see which is being applied).