Why is the ninth month called September?
c.1600, "press closely into something," from Latin impactus, past participle of impingere "to push into, dash against, thrust at" (see impinge). Originally sense preserved in impacted teeth (1876). Sense of "strike forcefully against something" first recorded 1916. Figurative sense of "have a forceful effect on" is from 1935. Related: Impacting.
1781, "collision," from impact (v.). Figurative sense of "forceful impression" is from 1817 (Coleridge).
impacted im·pact·ed (ĭm-pāk'tĭd)
Wedged together at the broken ends. Used of a fractured bone.
Placed in the alveolus in a manner prohibiting eruption into a normal position. Used of a tooth.
Packed in or wedged in such a manner so as to fill or block an organ or a passage.