Glabrousness (from the Latin glaber meaning "bald", "hairless", "shaved", "smooth") is the technical term for an anatomically atypical lack of hair, down or other such covering. This may be natural or due to loss because of a physical condition, such as alopecia universalis, which causes hair to fall out or prevents its growth.

In botany

In botany and mycology, a glabrous morphological feature is smooth, glossy, having no trichomes (bristles or hair-like structures), or glaucousness (see also indumentum). No plants have hair, although some structures may resemble it. Glabrous features may be an important means of identifying flora species. Glabrous characteristics of leaves, stems, and fruit are commonly used in plant keys.

The term is only used for features that lack trichomes at all times. When an organ has trichomes that are lost with age, the term used is glabrescent.

Glabrous skin

In varying degrees most mammals have some skin areas without natural hair. On the human body, glabrous skin is external skin that is naturally hairless. It is found on the ventral portion of the fingers, palms, soles of feet, lips, labia minora, and glans penis. Glabrousness is one trait that is associated with neoteny.