Meaning of PRO- in English

[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"

Merriam-Webster English vocab.      Английский словарь Merriam Webster.