Search Result for "superfecundation": 
Wordnet 3.0

NOUN (1)

1. fertilization of two or more ova released during the same menstrual cycle by sperm from separate acts of coitus (especially by different males); 



The Collaborative International Dictionary of English v.0.48:

Superfecundation \Su`per*fec`un*da"tion\, n. (Physiol.)
   Fertilization of two ova, at the same menstruation, by two
   different acts of coition.
   [1913 Webster]


WordNet (r) 3.0 (2006):

superfecundation
    n 1: fertilization of two or more ova released during the same
         menstrual cycle by sperm from separate acts of coitus
         (especially by different males)