Definition: ob-

Source: WordNet (r) 1.7

Ob
     n 1: a Russian river; flows northward to the Arctic Ocean [syn: Ob,
           Ob River]
     2: the branch of medicine dealing with childbirth and care of
        the mother [syn: obstetrics, OB, tocology, midwifery]

Source: Webster's Revised Unabridged Dictionary (1913)

Ob- \Ob-\ [L. ob, prep. Cf. Epi-.]
   A prefix signifying to, toward, before, against, reversely,
   etc.; also, as a simple intensive; as in oblige, to bind to;
   obstacle, something standing before; object, lit., to throw
   against; obovate, reversely, ovate. Ob- is commonly
   assimilated before c, f, g, and p, to oc-, of-, og-, and op-.

Source: The Free On-line Dictionary of Computing (2003-OCT-10)

Ob-

   /ob/ prefix Obligatory.  A piece of netiquette acknowledging
   that the author has been straying from the newsgroup's charter
   topic.  For example, if a posting in alt.sex is a response to
   a part of someone else's posting that has nothing particularly
   to do with sex, the author may append "ObSex" (or "Obsex") and
   toss off a question or vignette about some unusual erotic act.
   It is considered a sign of great winnitude when one's Obs
   are more interesting than other people's whole postings.

   [Jargon File]

Source: Jargon File (4.3.1, 29 Jun 2001)

Ob- /ob/ pref. Obligatory. A piece of netiquette acknowledging that
   the author has been straying from the newsgroup's charter topic. For
   example, if a posting in alt.sex is a response to a part of someone
   else's posting that has nothing particularly to do with sex, the author
   may append `ObSex' (or `Obsex') and toss off a question or vignette
   about some unusual erotic act. It is considered a sign of great
   winnitude when one's Obs are more interesting than other people's
   whole postings.