The number seven viewed collectively; a group composed of seven. Obsolete.

Also with capital initial. In Pythagorean philosophy: the number 4; (also) the sum of the first four numbers, namely 10. Cf. quaternary number n. at…

A set of four; the number four; esp. the Pythagorean name for the sum of the first four numbers (1 + 2 + 3 + 4 = 10) regarded as the source of all…

(in Pythagorean philosophy) = quaternion, n. 2; (loosely) the fact of there being four of something.

A sum, group, or set of four; four (things, etc.) regarded as a single object of thought.

The sum or number of seven; a group of seven.

Originally, in the Pythagorean system of numerology: the number five (now rare). Later: a group or set of five people or things.

Originally: †the number four (obsolete). Later: a set of or group of four; a compound entity with four component parts. Now rare.

a set of three pairs.

slang. The number three, in various connections; a set of three; a threepenny piece; spec. in the U.S., a three-dollar packet of a narcotic.