The Collaborative International Dictionary of English v.0.48:

Obit \O"bit\, n. [OF. obit, L. obitus, fr. obire to go against,
   to go to meet, (sc. mortem) to die; ob (see Ob-) + ire to go.
   See Issue.]
   1. Death; decease; the date of one's death. --Wood.
      [1913 Webster]

   2. A funeral solemnity or office; obsequies.
      [1913 Webster]

   3. A service for the soul of a deceased person on the
      anniversary of the day of his death.
      [1913 Webster]

            The emoluments and advantages from oblations, obits,
            and other sources, increased in value. --Milman.
      [1913 Webster]

   4. Same as obituary; -- by shortenting.
      [PJC]

   Post obit [L. post obitum]. See Post-obit.
      [1913 Webster]

WordNet (r) 3.0 (2006):

obit
    n 1: a notice of someone's death; usually includes a short
         biography [syn: obituary, obit, necrology]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

OBIT. That particular solemnity or office for the dead, which the Roman
Catholic church appoints to be read or performed over the body of a deceased
member of that communion before interment; also the office which, upon the
anniversary of his death, was frequently used as a commemoration or
observance of the day. 2 Cro. 51; Dyer, 313.