Pro always relates to the cause or reason for something happening or being done. Do not confuse it with por.
Cause = Because of, by reason of, on account of, for the sake of (cause), through, owing to, from, for, of.
Examples.—Li demandis ŝin, pro kio ŝi ploras = He asked her for what reason (because of what) she wept (weeps). Li min mokis pro mia kredemo = He ridiculed me owing to (for) my credulity. Li estas mortanta (or, ekmortas) pro (or, de) malsato = He is dying of (from) hunger. Ŝi agas pro ĵaluzemo = She acts from jealousy. Li ne povis piediri pro sia malforteco = He could not walk owing to (on account of, through) his weakness. Pro tio, mi ne povas akompani vin = On that account, I cannot accompany you. Li ĝin faris pro sia edzino = He did it because of his wife.
Pro is not used much as a prefix. Propeti = To intercede. Propekulo = A scapegoat.
259 (28). Sen = Without.
Sen always denotes disconnection.
Disconnection = Without, less, minus.
Examples.—Li alvenis sen sia amiko = He arrived without his friend. Sen vi, ni estus kiel sen kapo = Without you we should be as without a head. Dek sen tri estas sep = Ten less (minus) three is seven.
Sen is frequently used as a prefix, having the same meaning as our English suffix "less," as:—Sendube = Doubtless, without doubt. Sensenta = Senseless, without feeling. Sensenca = Senseless, without meaning. Senhonta = Shameless, without shame.
259 (29). Spite = In defiance of.[21]