cyclo-

American Heritage® Dictionary of the English Language, Fourth Edition

1. Circle; cycle: cyclorama.
2. A cyclic compound: cyclohexane.

Century Dictionary and Cyclopedia

1. n. An element in words of Greek origin, meaning ‘circle.’

Wiktionary

1. circle
2. cycle
3. chemistry a cyclic compound
4. meteorology cyclone

GNU Webster's 1913

1. A combining form meaning circular, of a circle or wheel.