All informal antonyms
in·for·mal
I i adj informal
- ceremonious — especially or excessively polite or formal
- official — a person appointed or elected to an office or charged with certain duties.
- rigid — stiff or unyielding; not pliant or flexible; hard: a rigid strip of metal.
- formal — being in accordance with the usual requirements, customs, etc.; conventional: to pay one's formal respects.
- stiff — rigid or firm; difficult or impossible to bend or flex: a stiff collar.
- buttoned-up — carefully planned, operated, supervised, etc.: one of the most buttoned-up companies in the business.