The Language of Clothing

[Janner52]

For my entire life blazer and sport jacket have been used interchangeably to refer to a "suit coat/jacket" that does not match the trousers.

Tan (khaki) pants & a dark blue jacket = slacks and and a blazer.

Matching pants & jacket = suit.

Matching pants, jacket & vest = three-piece suit.

I agree with the last two however sports jacket that originally referred to what was generally a tweed or similar looking jacket worn with plan trousers and in the day was referred to as casual wear.

A blazer was usually plain coloured, mostly navy blue, or striped and often with shiny buttons and an embroidered pocket badge.

This was the case in the UK.