I. prefix
Etymology: New Latin, from Latin, from Greek, before, forward, forth, for, from pro — more at for
1.
a. : earlier than : prior to : before
pro thalamion
b. : rudimentary : prot-
pro nucleus
c. : precursory
pro insulin
2.
a. : located in front of or at the front of : anterior to
pro cephalic
pro ventriculus
b. : front : anterior
pro thorax
3. : projecting
pro gnathous
II. prefix
Etymology: Latin pro in front of, before, for, forward — more at for
1. : taking the place of : substituting for
pro cathedral
pro caine
2. : favoring : supporting : championing
pro- American