Morrish Bible Dictionary 
Not used strictly for the descendants of one man. Numbers 26:29 refers to the descendants of Manasseh (No. 1, above) and Judges 11:1,40; Judges 12:7 to No. 2. We also read of Jair a Gileadite, Judges 10:3; and Barzillai, 2 Samuel 17:27; 2 Samuel 19:31; 1 Kings 2:7; Ezra 2:61; Nehemiah 7:63 . The Ephraimites accused the Gileadites and Jephthah with being fugitives from them, but they were severely punished for their arrogance. Judges 12:4-6 . Pekah when he revolted against Pekahiah slew fifty men of the Gileadites. 2 Kings 15:25 .
International Standard Bible Encyclopedia 
gil´ē̇ - ad - ı̄ts :
(1) A branch of the tribe of Manasseh ( Numbers 26:29 ).