The Collaborative International Dictionary of English v.0.48:

Entomb \En*tomb"\, v. t. [imp. & p. p. Entombed; p. pr. & vb.
   n. Entombing.] [Pref. en- + tomb: cf. OF. entomber.]
   To deposit in a tomb, as a dead body; to bury; to inter; to
   inhume. --Hooker.
   [1913 Webster]

WordNet (r) 3.0 (2006):

entomb
    v 1: place in a grave or tomb; "Stalin was buried behind the
         Kremlin wall on Red Square"; "The pharaohs were entombed in
         the pyramids"; "My grandfather was laid to rest last
         Sunday" [syn: bury, entomb, inhume, inter, lay to
         rest]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "entomb":
   bottle up, box in, box up, bury, cabin, casket, cloister, closet,
   coffin, conduct a funeral, confine, cramp, crib, encase, encoffin,
   ensepulcher, enshrine, hearse, immure, inearth, inhume, inter,
   inurn, lay away, lay to rest, plant, put, sepulcher, sepulture,
   shrine, straiten, tomb