Collins English Dictionary: English Words Starting With “O”
- on impulse
- on its last legs
- on its merits
- on key
- on leave
- on line
- on loan
- on message
- on no consideration
- on oath
- on occasion
- on offer
- on one side
- on one's back
- on one's beam-ends
- on one's best behaviour
- on one's conscience
- on one's deathbed
- on one's doorstep
- on one's feet
- on one's game
- on one's guard
- on one's hands
- on one's head
- on one's honour
- on one's lonesome
- on one's mettle
- on one's mind
- on one's own
- on one's own hook
- on one's own initiative
- on one's pat
- on one's plate
- on one's tod
- on one's toes
- on one's uppers
- on order
- on pain of
- on paper
- on parade
- on parole
- on pins and needles
- on principle
- on probation
- on purpose
- on record
- on relief
- on remand
- on request
- on schedule
- on seat