'Insecta' definitions:

Definition of 'Insecta'

noun

Insects; about five-sixths of all known animal species [syn: Insecta, class Insecta, Hexapoda, class Hexapoda]

From: GCIDE

Insecta \In*sec"ta\, n. pl. [NL. See Insect.]
1. (Zool.) One of the classes of Arthropoda, including those that have one pair of antenn[ae], three pairs of mouth organs, and breathe air by means of trache[ae], opening by spiracles along the sides of the body. In this sense it includes the Hexapoda, or six-legged insects and the Myriapoda, with numerous legs. See Insect, n. [1913 Webster]
2. (Zool.) In a more restricted sense, the Hexapoda alone. See Hexapoda. [1913 Webster]
3. (Zool.) In the most general sense, the Hexapoda, Myriapoda, and Arachnoidea, combined. [1913 Webster]
Note: The typical Insecta, or hexapod insects, are divided into several orders, viz.: Hymenoptera, as the bees and ants; Diptera, as the common flies, gnats, and mosquitos; Aphaniptera, or fleas; Lepidoptera, or moths and butterflies; Neuroptera, as the ant-lions and hellgamite; Coleoptera, or beetles; Hemiptera, as bugs, lice, aphids; Orthoptera, as grasshoppers and cockroaches; Pseudoneuroptera, as the dragon flies and termites; Euplexoptera, or earwigs; Thysanura, as the springtails, podura, and lepisma. See these words in the Vocabulary. [1913 Webster]