1. old gentleman - Noun
2. Old gentleman - Proper noun
the Old Gentleman
(euphemistic) The Devil.
(UK, slang, obsolete) A playing card that is almost imperceptibly longer than the others in the deck, used by cheats.
Used other than figuratively or idiomatically: see old, gentleman.
Source: en.wiktionary.orgI remember very well, when I was at Oxford, an old gentleman said to me, "Young man, ply your book diligently now, and acquire a stock of knowledge; for when years come upon you, you will find that poring upon books will be but an irksome task." Samuel Johnson
As one old gentleman put it, " Son, I don't care if you're stark nekkid and wear a bone in your nose. If you kin fiddle, you're all right with me. It's the music we make that counts. Robert Fulghum
PHILANTHROPIST, n. A rich (and usually bald) old gentleman who has trained himself to grin while his conscience is picking his pocket. Ambrose Bierce
At a certain spot the old gentleman would stop the carriage and take his son to a stone on the site of the Battle of Melrose (1526). Source: Internet
Later, seeing the results in the mirror, Cotten told Seiderman, "I am acting the part of a nice old gentleman, not a relief map of the Rocky Mountains." Source: Internet