Meaning of PRO in English

[pro] n, pl pros [ME, fr. L, prep., for--more at for] (15c) 1: an argument or evidence in affirmation "an appraisal of the ~s and cons"

2: the affirmative side or one holding it

[2]pro adv [pro-] (15c): on the affirmative side: in affirmation "much has been written ~ and con" [3]pro prep [L] (1837): in favor of: for [4]pro n or adj (1866): professional

Merriam-Webster English vocab.      Английский словарь Merriam Webster.