Circus \Cir"cus\, n.; pl. Circuses. [L. circus circle, ring, circus (in sense 1). See Circle, and cf. Cirque.]

1. (Roman Antiq.) A level oblong space surrounded on three sides by seats of wood, earth, or stone, rising in tiers one above another, and divided lengthwise through the middle by a barrier around which the track or course was laid out. It was used for chariot races, games, and public shows.

Note: The Circus Maximus at Rome could contain more than 100,000 spectators. --Harpers' Latin Dict.

2. A circular inclosure for the exhibition of feats of horsemanship, acrobatic displays, etc. Also, the company of performers, with their equipage.

3. Circuit; space; inclosure. [R.]

The narrow circus of my dungeon wall. --Byron.

Source: Webster's Revised Unabridged Dictionary (1913)