OFF

off colour (B2)

slightly unwell

off duty (B2)

not engaged in one's regular work

off the record (C1)

not made as an official statement / not for quotation

off balance (C2)

not physically balanced

off limits (C2)

barred to a designated group

off the beaten track (C2)

far away from other people, houses

off the cuff (C2)

without previous preparation

off the hook (C2)

no longer in difficulty or trouble

off the mark (C2)

a long way from an intended target

off the peg (C2)

(of clothes) ready

off your rocker (C2)

be crazy