Meaning of おっさん in Japanese

Definition of おっさん

おっさん(ossan)

Now that I think of it, I've been asked to look at a haiku he'd written by the tipsy bloke sitting next to me on the train.

おい、おっさん！何やってんだよ！

Hey, pops! What are you doing!

To me he's no different from a million other dull middle aged men.

「おっさん、やさしいなー」ウィリーは言った。

"That's very nice of you," Willie answered.

「おっさん、やさしいなー。」ウィリーは言った。

"That's very nice of you," Willie answered.