Glabrousness

Glabrousness (from the Latin meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, such as alopecia universalis in humans, which causes hair to fall out or not regrow. Humans may also intentionally remove some or all of their body hair for a variety of cultural reasons.

In botany and mycology, a glabrous morphological feature is smooth and often glossy, having no bristles or hair-like structures (trichomes). No plants have hair, although some structures may resemble it. Glabrous characteristics of leaves, stems, and fruit are commonly used features 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.

In varying degrees most mammals have some skin areas without natural hair. On the human body, glabrous skin is found on the ventral portion of the fingers, palms, soles of feet and lips, which are all parts of the body most closely associated with interacting with the world around us, as are the labia minora and glans penis. There are four main types of mechanoreceptors in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles.

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