From Latin 'circulus,' diminutive of 'circus' (ring) — a little ring that grew to encompass geometry and social groups.
A round plane figure whose boundary consists of points equidistant from a fixed center; a group of people sharing a common interest or activity; a sequence that finishes at its starting point.
English 'circle' comes from Old French 'cercle' and directly from Latin 'circulus' (a circular figure, a small ring), which is the diminutive of 'circus' (a ring, a circular arena). Latin 'circus' was borrowed from Greek 'kírkos' or 'kríkos' (κρίκος), meaning 'a ring.' The Greek word has no established Indo-European etymology and may be a pre-Greek substrate word. English acquired the word twice: once in Old English as 'circul' (directly from Latin
English 'circle' and 'circus' are the same word at different levels of magnification: 'circulus' is literally the diminutive ('little ring') of 'circus' ('ring'). The Circus Maximus in Rome was not a place for clowns but a vast circular racetrack for chariots — the word only gained its modern 'big top' sense in the 18th century.