ABI AND AB IN PROPER NAMES (Jewish Encyclopedia)

From BibleWiki

Abi and Ab are used both as the first element, as in Abijah, Abishur, Abinoam, Abner, and as the second element, as in Eliab, Joab, and Ahab. Theirexact meaning is still under dispute. Each of the foregoing proper names may be a sentence; for example, Abinoam="Father is pleasantness"; or it may be only a phrase, as "Father of pleasantness." Further, the i in Abi may be either the connecting vowel or the pronominal suffix (first person). The weight of authority favors the sentence form. Opinions differ as to the phrase form; but it is safe to say that the forms with the connecting vowel and with the suffix have been confused, so that the translation will depend largely on the other element in the name (Gray, "Hebrew Proper Names," pp. 22-34, 75-86; see also Names).