A humanoid was an organic or mechanical being similar in overall form to a Human, the most common sentient species. The term is less specific than Near-Human, which generally implies common biological ancestry with Humans. Classification of a being as humanoid was not standardized or strict. Generally, it entailed having a basic anatomy or construction similar to Humans, that is, a central torso with a head on top, two arms symmetrically arranged on either side, and two legs symmetrically arranged below, providing an upright bipedal stance. Each arm ended in hands that had a variable number of fingers (used for grasping and moving objects), and each leg in feet (used for locomotion). A living humanoid's head had two eyes, a nose for breathing and smelling, and a mouth for nutrition and communication; a mechanical humanoid would not require respiration or nutrition, and would have two photoreceptors instead of eyes. Humanoid species generally had sparse hair, mainly concentrated on the head or face.
Non-humanoid sentient species had distinctly nonhuman characteristics, such as tails, additional limbs (or even no limbs), wings, additional heads, or invertebrate characteristics.