designer, elegant, immaculate, smart (esp. BrE), well-cut (esp. BrE), well-tailored (esp. AmE)
ill-fitting
best, good
He wore his one good suit to the interview.

expensive
tailored
double-breasted, single-breasted
one-piece, two-piece, three-piece
pinstripe, pinstriped
linen, seersucker (esp. AmE), tweed, wool, etc.
summer
business, dinner (BrE), dress, formal, lounge (BrE), morning, safari, zoot
pant (usually pantsuit), trouser (BrE)
bathing, diving, swim (usually swimsuit), swimming (esp. AmE)
jogging (BrE), ski
leisure (AmE), shell (BrE), sweat (usually sweatsuit)
warm-up (AmE)
biohazard, boiler (esp. BrE), hazmat (AmE), protective
flying, pressure
clown, gorilla

coat (AmE), jacket, pants (AmE), trousers (esp. BrE)

in a suit
Two men in suits came out of the hotel.

a suit and tie
They won't let you into the restaurant without a suit and tie.

a suit of armour/armor
The cavalry wore a suit of light armour/armor and carried a shield.

a suit of clothes (old-fashioned)
His parents had bought him a new suit of clothes for the occasion.
We bought the baby a couple of suits of clothes.

civil (esp. AmE)
class-action (AmE)
paternity
antitrust, discrimination, libel, malpractice (all esp. AmE)

bring, file
A suit has been filed against the company.

be involved in, pursue
drop
They have agreed to drop their suit against the Dutch company.

be faced with, face
The company now faces several suits over its failure to protect its employees.

defend
She plans to defend the suit vigorously.

win
lose
settle
The two companies have settled the suit.

dismiss

in a/the suit
They are seeking damages in a lawsuit.

suit against
a suit against her former husband

suit over
a suit over a disputed estate