Alternative form of there's many a slip twixt cup and lip

present participle of slip under the radar

An orchid of the subfamily Cypripedioideae, distinguished by their slipper-shaped pouches which trap insects to improve pollination rates. / The type species of this subfamily, Cypripedium calceolus.

A low soft shoe that can be slipped on and off easily. / Such a shoe intended for indoor use; a bedroom or house slipper. / (US, Hawaii, Singapore) A flip-flop (type of rubber sandal).

(obsolete) slippery

(UK, Australia, New Zealand) To spank with a plimsoll as corporal punishment.

Done poorly or too quickly; slapdash. / (obsolete) Wearing slippers or similarly open shoes.

Of a surface, having low friction, often due to being covered in a non-viscous liquid, and therefore hard to grip, hard to stand on without falling, etc.

A fitted protective or decorative cover that may be slipped off and on a piece of upholstered furniture, usually made of cloth.

(figuratively) A chain of events that, once initiated, cannot be halted; especially one in which the final outcome is undesirable or precarious.