(given, dedicated), as applied specifically to a distinct body of men connected with the services of the temple, this name first meets us in the later books of the Old Testament—in 1 Chronicles, Ezra and Nehemiah. The word and the ideas embodied in it may, however, be traced to a much earlier period. As derived from the verb nathan, i.e. give, set apart, dedicate, it was applied to those who were pointed to the liturgical offices of the tabernacle. We must not forget that the Levites were given to Aaron and his sons, i.e. to the priests as an order, and were accordingly the first Nethinim (Numbers 3:9; 8:19). At first they were the only attendants, and their work must have been laborious enough. The first conquests, however, brought them their share of the captive slaves of the Midianites, and 320 were given to them as having charge of the tabernacle (Numbers 31:47), while 32 only were assigned specially to the priests. This disposition to devolve the more laborious offices of their ritual upon slaves of another race showed itself again in the treatment of the Gibeonites. No addition to the number thus employed appears to have been made during the period of the judges, and they continued to be known by their own name as the Gibeonites. Either the massacre at Nob had involved the Gibeonites as well as the priests (1 Samuel 22:19), or else they had fallen victims to some other outburst of Saul’s fury, and though there were survivors (2 Samuel 21:2), the number was likely to be quite inadequate for the greater stateliness of the new worship at Jerusalem. It is to this period accordingly that the origin of the class bearing this name may be traced. The Nethinim were those “whom David and the princes appointed (Hebrew, gave) for the service of the Levites” (Ezra 8:20). At this time the Nethinim probably lived within the precincts of the temple, doing its rougher work and so enabling the Levites to take a higher position as the religious representatives and instructors of the people. The example set by David was followed by his successor.
Smith's Bible Names Dictionary (1866).