WordNet (r) 3.0 (2006):

Michael
    n 1: (Old Testament) the guardian archangel of the Jews

Easton's 1897 Bible Dictionary:

Michael
   who is like God? (1.) The title given to one of the chief angels
   (Dan. 10:13, 21; 12:1). He had special charge of Israel as a
   nation. He disputed with Satan (Jude 1:9) about the body of
   Moses. He is also represented as warning against "that old
   serpent, called the Devil, and Satan, which deceiveth the whole
   world" (Rev. 12:7-9).

     (2.) The father of Sethur, the spy selected to represent Asher
   (Num. 13:13).

     (3.) 1 Chr. 7:3, a chief of the tribe of Issachar.

     (4.) 1 Chr. 8:16, a Benjamite.

     (5.) A chief Gadite in Bashan (1 Chr. 5:13).

     (6.) A Manassite, "a captain of thousands" who joined David at
   Ziklag (1 Chr. 12:20).

     (7.) A Gershonite Levite (1 Chr. 6:40).

     (8.) The father of Omri (1 Chr. 27:18).

     (9.) One of the sons of king Jehoshaphat (2 Chr. 21:2, 4). He
   was murdered by his brother Jehoram.