In the UK, "geezer" is just slang for man. It has no age limit and it's not rude. However, if you say someone is "a bit of a geezer" it means he's involved in illegal stuff maybe, not to be trusted. "Old geezer" is an old man and it's not polite to refer to an elderly man in that way.

Hey In the United States, geezer commonly means an old man and it’s usually an insulting term. However, things are quite a bit different over in Great Britain. The word geezer in the UK can be used to refer to pretty much any man, young or old. Even more drastically different, geezer is occasionally used as a compliment for an outstanding guy. That’s not to say that geezer is never insulting. Some treat it as a mildly negative term for the men in their lives, although this isn’t just limited to older gentlemen. Geezer can be used in a few different ways. The first way is commonly for just about any man you’ll meet, regardless of his age. This version has a neutral meaning with no negative connotations. You would say it something like this: “There was some geezer waiting outside the pub.” Depending on your tone of voice with the above sentence, you can make geezer sound purely neutral or a bit more negative. It’s up to you based on whatever your intent is. In rare cases, the word geezer is actually a compliment. You’ll want to use some complementary words around it or a positive tone to indicate that’s the case with a sentence like this: “Paul is a bloody brilliant geezer.” If anything, the word geezer teaches us not to make assumptions. Many people are used to hearing the word used in a pejorative fashion. However, in British terminology, the word is not only generally neutral – it can, on occasion, be positive! I hope it brought more clarity :)

No, it’s generally neutral, and often used to refer to someone you don’t know : ‘This geezer came up to me and said . . ‘ It tends to be used for older men, often ‘old geezer’, and it can be complimentary : ‘He’s a great geezer’ or ‘he’s a diamond geezer’ - cockney [London working class] slang for a ‘great bloke’ - a man you really like or admire.

I would agree with the other comments. In Britain, geezer means man. We can say 'he's a top geezer' as a compliment. We can say 'this geezer asked me for the time' in a neutral sense'. 'Old geezer' is not complimentary. However, if someone has a prominent social position, such as a politician or senior police officer or doctor, and we refer to them as 'that geezer', then this is a form of insult because it's downgrading their status.

In the US, geezer is almost always prefaced with "old." The old geezer can't even turn on a computer. When it is used relative to a person that is not present, it is pejorative. It implies that the person's mind and/or body are declining. My son can come in the house and ask "How's it going old geezer?" In that case, it is a little affectionate and a little bit of attempt to get a reaction from me.