Meaning

noun everything that is included in a collection and that is held or included in something

noun what a communication that is about something is about

noun the proportion of a substance that is contained in a mixture or alloy etc.

originFrom Middle English content (plural contentes, contence), from Latin contentus, past participle of continēre (“to hold in, contain”), as Etymology 1, above. English apparently developed a substantive form of the adjective, which is not mirrored in Romance languages.

Etymology from Wiktionary, CC BY-SA 3.0