(probability theory) The counterintuitive observation that a random group of people needs to have only 23 members before there is a 50% chance of two of them having the same birthday.

plural of parasol ant

leaf-cutter ant

(engineering) Any linkage by which circular motion may be changed into motion in a straight line.

A geometrical instrument for drawing parallel lines.

plural of parallel ruler

(ornithology) Practicing brood parasitism.

(idiomatic, vulgar) To rain on someone's parade.

austral parakeet

A census-designated place in Santa Cruz County, California, United States.