The Collaborative International Dictionary of English v.0.48:

cum \cum\ (k[u^]m; k[oo^]m), prep. [L. with prep.]
   with; together with; along with; as, I work at home in an
   office-cum-bedroom.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

cum \cum\ (k[u^]m), n.
   same as semen[2]; -- also spelled come. [vulgar slang]
   [PJC]

WordNet (r) 3.0 (2006):

cum
    n 1: the thick white fluid containing spermatozoa that is
         ejaculated by the male genital tract [syn: semen, seed,
         seminal fluid, ejaculate, cum, come]