(ē'tē-ō), 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.
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.