[on the safe side] {adv. phr.} Provided for against a possible […]

[on the shelf] {adv.} or {adj. phr.}, {informal} Laid aside; not […]

[on the side] {adv. phr.}, {informal} 1. In addition to a […]

[on the sly] {adv. phr.} So that other people won't know; […]

[on the spot] {adv.} or {adj. phr.} 1. or [upon the […]

[on the spur of the moment] {adv. phr.} On a sudden […]

[on the stage] {adv.} or {adj. phr.} In or into the […]

[on the string] or [on a string] {adv. phr.}, {informal} Under […]

[on the take] {adv. phr.} Bribable; corrupt. * /Officer O'Keefe was […]

[on the tip of one's tongue] {adv. phr.} About to say […]