From BiblePortal Wikipedia

Smith's Bible Dictionary [1]

Zif.  1 Kings 6:1. See Month .

American Tract Society Bible Dictionary [2]

The second month of the Hebrew year, also called Iyar, and nearly corresponding to our May,  1 Kings 6:1 .

Easton's Bible Dictionary [3]

 1 Kings 6:1,37Month

Webster's Dictionary [4]

(n.) The second month of the Jewish ecclesiastical year, corresponding to our May.

Morrish Bible Dictionary [5]

See Months

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

(Heb. Ziv, זְו , Bloom; Sept. Ζιού v.r. Νεισώ , Vulg. Zio ) , the early name ( 1 Kings 6:1;  1 Kings 6:37) of the second Hebrew month IYAR (See Iyar) (q.v.), corresponding to April or May. (See Calendar).

Kitto's Popular Cyclopedia of Biblial Literature [7]

Zif (bloom-month), an ante-Exilian name of the second Hebrew month (), corresponding with our April and May. This, the second month of the sacred, was the eighth of the civil year. The second month bore also the name Iyar.