Nethinim - (Easton's Bible Dictionary)
The name given to the hereditary temple servants in all the post-Exilian books of Scripture. The word means given, i.e., "those set apart", viz., to the menial work of the sanctuary for the Levites. The name occurs seventeen times, and in each case in the Authorized Version incorrectly terminates in "s", "Nethinims;" in the Revised Version, correctly without the "s" (Ezra 2:70; 7:7, 24; 8:20, etc.). The tradition is that the Gibeonites (Josh. 9:27) were the original caste, afterwards called Nethinim. Their numbers were added to afterwards from captives taken in battle; and they were formally given by David to the Levites (Ezra 8:20), and so were called Nethinim, i.e., the given ones, given to the Levites to be their servants. Only 612 Nethinim returned from Babylon (Ezra 2:58; 8:20). They were under the control of a chief from among themselves (2:43; Neh. 7:46). No reference to them appears in the New Testament, because it is probable that they became merged in the general body of the Jewish people.