[pro-] prefix [ME, fr. OF, fr. L, fr. Gk, before, forward, forth, for, fr. pro--more at for] 1 a: earlier than: prior to: before "prothalamion" b: rudimentary: prot- "pronucleus" c: precursory "proinsulin"
2. a: located in front of or at the front of: anterior to "procephalic" "proventriculus" b: front: anterior "prothorax"
3: projecting "prognathous"
[2]pro- prefix [L pro in front of, before, for, forward--more at for] 1: taking the place of: substituting for "procathedral" "procaine"
2: favoring: supporting: championing "pro-American"