Meaning

verb have as a part, be made up out of

verb consider as part of something

verb add as part of something else; put in as part of a set, group, or category

originFrom Middle English includen, borrowed from Latin inclūdere (“to shut in, enclose, insert”), from in- (“in”) + claudere (“to shut”), ultimately from Proto-Indo-European *kleh₂w- (“key, hook, nail”). Doublet of enclose. Displaced native Old English belūcan (“to include,” also “to shut in”).

Etymology from Wiktionary, CC BY-SA 3.0