[on the block] {adj. phr.} To be sold; for sale. * […]

[on the brain] {adj. phr.}, {slang} Filling your thoughts; too much […]

[on the brink of] {adv. phr.} Facing a new event that's […]

[on the button] {adv., adj.}, {slang} At the right place; at […]

[on the cards] See: [IN THE CARDS]

[on the carpet] See: [CALL ON THE CARPET].

[on the cheap] {adv. phr.} Inexpensively; on a tight budget. * […]

[on the chin] See: [TAKE IT ON THE CHIN].

[on the contrary] {adv. phr.} Exactly the opposite; rather; instead. * […]

[on the cuff] {adj.} or {adv. phr.}, {informal} Agreeing to pay […]