In biology, integument is the natural covering of an organism or an organ, such as its skin, husk, shell, or rind.
It derives from integumentum, which means "a covering" in Latin. In a transferred or figurative sense, it could mean a cloak or a disguise. In English "integument" is a fairly modern word, its origin having been traced back to the early seventeenth century. It can mean a material or layer with which anything is enclosed, clothed, or covered in the sense of "clad" or "coated", as with a skin or husk.
In botany the senses are similar to those in zoology, referring to the covering of an organ, but when the context indicates nothing to the contrary, the word commonly refers to an envelope of one or more layers, each of two or more cell layers, covering the ovule, leaving only a pore, the micropyle, through which the pollen tube can enter. It may develop into the testa, or seed coat.
The integument of an organ in zoology typically would comprise membranes of connective tissue such as those around a kidney or liver. In referring to the integument of an animal, the usual sense is its skin and its derivatives: the integumentary system, where "integumentary" is a simile for "cutaneous".
In arthropods, the integument, or external "skin", consists of a single layer of epithelial ectoderm from which arises the cuticle, an outer covering of chitin the rigidity of which varies as per its chemical composition.
Derivative terms and sundry usages
Derivative terms include various adjectival forms such as integumentary (e.g. system), integumental (e.g. integumental glands, "peltate glands, the integument being raised like a bladder due to abundant secretion") and integumented (as opposed to bare).
Other illustrative examples of usage occur in the following articles: