A prefix in many words of Latin origin. It signifies from, away , separating, or departure, as in abduct, abstract, abscond. See A-(6).
English prefix. In Latin it was both a prefix and a preposition meaning ""off, away (from)" and expressed the idea of removal, ab- sense, separation, or a lower value. It first appeared in English in the Middle English period in words borrowed from Old French, and continued to be borrowed in Modern French words and eventually from Classical Latin, especially in the vocabulary of science, medicine, botany, etc.