The Collaborative International Dictionary of English v.0.48:

bollock \bollock\ n.
   one of the two male reproductive glands; a testis; -- usually
   spelled ballock, and usually used in the plural.

   Syn: gonad, testicle, ball, nut, egg.
        [WordNet 1.5 +PJC]

   2. a pulley-block at the head of a topmast.

   Syn: bullock block.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

ballock
    n 1: one of the two male reproductive glands that produce
         spermatozoa and secrete androgens; "she kicked him in the
         balls and got away" [syn: testis, testicle, orchis,
         ball, ballock, bollock, nut, egg]