Buddy-American, Canada. Mate- UK, Australia, NZ.

Hi Sol One of my Russian students (who is learning English) was talking about this the other day. He said that the Russian language has a whole range of words which express different levels of friendship, and that in his opinion it's not really possible to translate all of these concepts of different grades of friendship into English, because we simply don't have the same cultural ideas. I'm not really sure if this is true or not (I don't speak Russian for a start), but obviously your question is interesting for me, after having that conversation I note that you ask about synonyms for 'friend'. Robert's comment above has given you a good description of some of the nuances of meaning, and I don't think it's necessary to add to that. Also, you say this is for 'an essay'. The word 'essay' normally describes a formal piece of writing in English. Often associated with academic study. In this context, I'm not sure I would use any of the synonyms, unless you are completely confident that they can be applied to the context you are writing about, because all of the meanings are a bit different (as Robert described).

I totally agree with you. Buddy is more formal than mate. because mate mostly deals with soulmate or playmate. In essay Buddy is more formal.

In my opinion formal: companion, confidant (knows your secrets) informal: buddy, mate, pal, chum - these are interchangeable, though mate is not often used in the USA and chum is not often used comrade - military-like crony - criminal-like or devious, for example, a political crony alter ego - special friend who has opposite characteristics playmate - child's friend soul mate - spouse, lover or very special friend who has very similar characteristics