The 300th anniversary of an event or happening.

Occurring every three hundred (300) years.

A grouping of three. / A word of three syllables. / A branch of a Chinese underground criminal society, mostly based in Hong Kong.

(geometry) A right triangle.

(geometry) An obtuse triangle.

(geometry) A triangle all of the angles of which are acute.

(geometry) An acute triangle.

(geometry) A triangle one of whose angles is obtuse.

(geometry) A triangle having a right angle as one of its interior angles.

hard to deal with, complicated / adept at using deception / (colloquial, slang) Relating to or associated with a prostitution trick