One of the fine strands that grow from the skin of mammals, usually providing insulation against the cold. Modified hairs sometimes serve as protective defenses, as in the quills of a porcupine or hedgehog, or as tactile organs, as in the whiskers (called vibrissae) of many nocturnal mammals. Hair filaments are a modification of the epidermis of the skin and are composed primarily of keratin. Hair also contains melanin, which determines hair color.
A slender growth resembling a mammalian hair, found on insects and other animals.
A fine, threadlike growth from the epidermis of plants. See more at trichome.
tear (tîr) Pronunciation Key
A drop of the clear salty liquid secreted by glands (lacrimal glands) in the eyes. Tears wet the membrane covering the eye and help rid the eye of irritating substances.