Noun
(UK, dated) Synonym of old chap (“affectionate term of address for a man”)
(UK, colloquial) Synonym of old chap (“the penis”)
Source: en.wiktionary.orgWhen I was young, the old regarded me as an outrageous young fellow, and now that I'm old the young regard me as an outrageous old fellow. Fred Hoyle
I gathered that the old fellow suffers from some advanced form of senile dementia, and so perhaps his analysis is not totally accurate. Jack Vance
I was hoping the bishop would be coming himself. He's a terribly agreeable old chap. I always find it so enjoyable to blether with the old fellow. We don't agree about anything. But everything depends on agreeing to disagree. Halldór Laxness
There was no last animal I treated. When young farm lads started to help me over the gate into a field or a pigpen, to make sure the old fellow wouldn't fall, I started to consider retiring. James Herriot
He's enormously rich and very generous, and the most learned old fellow in Britain." Source: Internet
The old fellow held the radish up high by its tail and inspected it. Source: Internet