= rock, n.1 6a.

As a count noun: a case or cause of danger; something dangerous or harmful. In plural: dangers, risks. †at all perils: at whatever risk, whatever…

A thing to be dreaded; danger, risk. Obsolete.

A dangerous whirlpool on the coast of Sicily (now Calofaro), opposite the Italian rock Scylla. Used allusively of anything likely to cause…

In figurative or allusive uses. A source of danger or destruction, chiefly with allusion to shipwreck.

As a count noun. A risk of loss or harm posed by something; a possibility of danger or an adverse outcome; a condition or situation involving such a…

(with a and plural) An instance or cause of danger; plural perils, risks.

= shelf, n.2 Also in combination †shelveflat.

figurative. Something which causes a principle, proposal, etc., to founder; a hidden obstacle or hazard.

kittly-benders n. kettle-de-benders n. thin ice which bends under one's weight; the sport of running over this. (U.S. colloquial.)

In general use: anything which causes, or is capable of causing a person to twist or break an ankle. Frequently hyperbolical. Also as a modifier.

(in sense 2; also figurative).