1. Prefix used with, for example, cholane to indicate replacement of the C-17 side chain by H; thus, etiocholane is the 5β isomer of androstane.
2. Combining form meaning cause.
prefix meaning "causation": etiology.
aetio-The Greek root for “cause”, as in aetiology.
etio-[Gr. aitia, cause]
Prefix meaning causation. The variant aetio- is used outside the U.S.