The Collaborative International Dictionary of English v.0.48:

Levite \Le"vite\ (l[=e]"v[imac]t), n. [L. Levites, Gr.
   Leyi:`ths, fr. Heb. Levi, one of the sons of Jacob.]
   1. (Bib. Hist.) One of the tribe or family of Levi; a
      descendant of Levi; esp., one subordinate to the priests
      (who were of the same tribe) and employed in various
      duties connected with the tabernacle first, and afterward
      the temple, such as the care of the building, bringing of
      wood and other necessaries for the sacrifices, the music
      of the services, etc.
      [1913 Webster]

   2. A priest; -- so called in contempt or ridicule.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Levite
    n 1: a member of the Hebrew tribe of Levi (especially the branch
         that provided male assistants to the temple priests)

Easton's 1897 Bible Dictionary:

Levite
   a descendant of the tribe of Levi (Ex. 6:25; Lev. 25:32; Num.
   35:2; Josh. 21:3, 41). This name is, however, generally used as
   the title of that portion of the tribe which was set apart for
   the subordinate offices of the sanctuary service (1 Kings 8:4;
   Ezra 2:70), as assistants to the priests.

     When the Israelites left Egypt, the ancient manner of worship
   was still observed by them, the eldest son of each house
   inheriting the priest's office. At Sinai the first change in
   this ancient practice was made. A hereditary priesthood in the
   family of Aaron was then instituted (Ex. 28:1). But it was not
   till that terrible scene in connection with the sin of the
   golden calf that the tribe of Levi stood apart and began to
   occupy a distinct position (Ex. 32). The religious primogeniture
   was then conferred on this tribe, which henceforth was devoted
   to the service of the sanctuary (Num. 3:11-13). They were
   selected for this purpose because of their zeal for the glory of
   God (Ex. 32:26), and because, as the tribe to which Moses and
   Aaron belonged, they would naturally stand by the lawgiver in
   his work.

     The Levitical order consisted of all the descendants of Levi's
   three sons, Gershon, Kohath, and Merari; whilst Aaron, Amram's
   son (Amram, son of Kohat), and his issue constituted the
   priestly order.

     The age and qualification for Levitical service are specified
   in Num. 4:3, 23, 30, 39, 43, 47.

     They were not included among the armies of Israel (Num. 1:47;
   2:33; 26:62), but were reckoned by themselves. They were the
   special guardians of the tabernacle (Num. 1:51; 18:22-24). The
   Gershonites pitched their tents on the west of the tabernacle
   (3:23), the Kohathites on the south (3:29), the Merarites on the
   north (3:35), and the priests on the east (3:38). It was their
   duty to move the tent and carry the parts of the sacred
   structure from place to place. They were given to Aaron and his
   sons the priests to wait upon them and do work for them at the
   sanctuary services (Num. 8:19; 18:2-6).

     As being wholly consecrated to the service of the Lord, they
   had no territorial possessions. Jehovah was their inheritance
   (Num. 18:20; 26:62; Deut. 10:9; 18:1, 2), and for their support
   it was ordained that they should receive from the other tribes
   the tithes of the produce of the land. Forty-eight cities also
   were assigned to them, thirteen of which were for the priests
   "to dwell in", i.e., along with their other inhabitants. Along
   with their dwellings they had "suburbs", i.e., "commons", for
   their herds and flocks, and also fields and vineyards (Num.
   35:2-5). Nine of these cities were in Judah, three in Naphtali,
   and four in each of the other tribes (Josh. 21). Six of the
   Levitical cities were set apart as "cities of refuge" (q.v.).
   Thus the Levites were scattered among the tribes to keep alive
   among them the knowledge and service of God. (See PRIEST.)