adjectival comes from adjective + -al, from Latin adiectivum ('that is added'), from adiectus, past participle of adicere ('to throw to, add'), from ad- ('to') + iacere ('to throw'). Morphologically, the word is transparent: -al is attached to the older base named in the history, so the modern form packages an inherited or borrowed stem inside a later English derivative. In modern use, the adjective sense is "relating to or functioning as an adjective", which keeps the etymology connected to the word's present dictionary value rather than treating it as a merely historical label. The wider word family includes related English forms such as adjective and derivatives such as adjectivally, showing how the same base continues to support neighboring English vocabulary. The principal historical forms in the chain include Latin adiectivum, Latin iacere, which anchor the explanation in named linguistic material.