1. 
[syn: biological, biologic]
2.  of parents and children;  related by blood; 
- Example: "biological child"
The Collaborative International Dictionary of English v.0.48:
Biologic \Bi`o*log"ic\, Biological \Bi`o*log"ic*al\, a.
   1. Of or relating to biology. -- Bi`o*log"ic*al*ly, adv.
      [1913 Webster]
   2. related by blood; -- of parents and children; --
      contrasted with adoptive, adopted, or foster; as,
      Mary was adopted directly from the maternity hospital and
      never met her biological mother.
   Syn: biologic.
        [WordNet 1.5]
WordNet (r) 3.0 (2006):
biological
    adj 1: pertaining to biology or to life and living things [syn:
           biological, biologic]
    2: of parents and children; related by blood; "biological child"
       [ant: adoptive]