Had

King James Dictionary

Had, pret. and pp. of have contracted from Sax.haefd, that is, haved as, I had I have had. In the phrase, "I had better go," it is supposed that had is used for would "I'd better go." The sense of the phrase is, "it would be better for me to go."

Webster's Dictionary

(1): ( imp. & p. p.) of Have

(2): ( imp. & p. p.) See Have.