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c.1600, from Latin (animal) insectum "(animal) with a notched or divided body," literally "cut into," from neuter past participle of insectare "to cut into, to cut up," from in- "into" (see in- (2)) + secare "to cut" (see section (n.)). Pliny's loan-translation of Greek entomon "insect" (see entomology), which was Aristotle's term for this class of life, in reference to their "notched" bodies.
First in English in 1601 in Holland's translation of Pliny. Translations of Aristotle's term also form the usual word for "insect" in Welsh (trychfil, from trychu "cut" + mil "animal"), Serbo-Croatian (zareznik, from rezati "cut"), Russian (nasekomoe, from sekat "cut"), etc.
insect in·sect (ĭn'sěkt')
Any of numerous usually small arthropod animals of the class Insecta, having an adult stage characterized by three pairs of legs and a body segmented into head, thorax, and abdomen and usually having two pairs of wings.
Any of various similar arthropod animals, such as spiders, centipedes, or ticks.
Any of very numerous, mostly small arthropods of the class Insecta, having six segmented legs in the adult stage and a body divided into three parts (the head, thorax, and abdomen). The head has a pair of antennae and the thorax usually has one or two pairs of wings. Most insects undergo substantial change in form during development from the young to the adult stage. More than 800,000 species are known, most of them beetles. Other insects include flies, bees, ants, grasshoppers, butterflies, cockroaches, aphids, and silverfish. See Notes at biomass, bug, entomology.