Easton's Bible Dictionary (1897)
Known. (1.) One of the chiefs who subscribed the covenant (Neh. 10:21). (2.) The last high priest mentioned in the Old Testament (Neh. 12:11, 22), sons of Jonathan.
Smith's Bible Dictionary (1863)
(known).
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
JADDU'A (known). One who sealed the covenant. Neh 10:21. The son of Jonathan, high priest of the Jews, who officiated a considerable time after the Captivity, and who is believed to be the same who lived in the time of Alexander the Great "by those who maintain that the list, Neh 12:11, of high priests from Joshua to Jaddua, or from b.c. 538-b.c. 336, cannot, in its present shape, have proceeded from Nehemiah's hand, or from that of a
contemporary." -Bible (Speaker's) Commentary. He is the last of the high priests mentioned in the O.T.
Hitchcock's Bible Names (1869)
known