A composite was a combination of anatomical features.

In 2366, Data programmed several thousand composites for his then-formless child Lal to choose from in USS Enterprise-D's holodeck. Lal ultimately chose a Human female appearance. (TNG: "The Offspring")

Composites

Andorian female
Played by Kristina Kochoff

Human male
Played by an Andy Wiley

Klingon male
Played by an unknown actor