ADONIKAM (ăd-ō-nī'kăm, Heb. ’ădhōnîqām, my Lord has arisen). The ancestor of a family, 666 of whom returned from exile with Zerubbabel (Ezra.2.13). Among the chiefs of the people who returned with Ezra are three sons and sixty males of this family (Ezra.8.13). In the list of exiles whose genealogy proved them Israelites are 667 of this family (Neh.7.18). The Adonijah of Neh.10.16, because of his position among those who sealed the covenant, is thought to be the same as Adonikam.
International Standard Bible Encyclopedia (1915)
The name of a family of the returning exiles (Ezr 2:13; Ne 7:18). "The sons of Adonikam," men and women and children, numbered 666 according to the list as given in Ezr, but 667 according to the copy in Neh. Either included among these or in addition to them was the contingent that came with Ezr, "Ehphalet, Jeuel, and Shemaiah, and with them 60 males" (Ezr 8:13).