ana·bolic (n-blk) adj.

Anabolic is a metabolic process that turns smaller units into larger units.  The anabolic process builds up muscle tissue and produces growth which results in larger muscle size. 

Anabolic is a chemical reaction where small molecules are combined to make larger molecules, this happens when amino acids are combined and become polypeptite chains that become protein strands.  The protein strands then become muscle tissue.

Anabolic Steroids are steroid molecules that are similar to testosterone, the hormone naturally produced within our own body.   Anabolic steroids stimulate a anabolic reaction in the body,  increasing protein synthesis,  which builds cellular tissue in muscles.