Dictionary.com
definitions

feti-

  1. a combining form representing fetus or fetal in compound words: fetoscope.
Also especially before a vowel, fet-, feto-.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
fet- in Medicine

fet-

pref.
  1. Variant offeto-
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.