Something that is added; an addition or supplement, especially in legal or scholarly contexts.
Direct borrowing from Latin 'additum' (a thing added), the neuter past participle of 'addere' (to add). It appears in formal English primarily in legal and academic Latin phrases.
You'll find this word in old legal documents written in Latin or English legal writing that preserves Latin terms—it's the formal way lawyers once referred to added clauses or supplementary items.
Complete word intelligence in one call. Free tier — 50 lookups/day.