means A suit is a matched set of garments (typically a jacket and trousers or skirt) worn together as formal or business attire — or, by extension, the powerful person wearing one.

from From Old French 'suite,' meaning a following or sequence — the same root that gives us 'suite' and 'pursue,' all tracing back to Latin 'sequi,' to follow. A suit was literally things that 'followed' one another as a matched set; the clothing sense (a coat and trousers cut to go together) grew from that idea of pieces belonging in a series. The 'card suit' and 'lawsuit' (something you 'follow' through court) bloom from the same Latin seed.