Entry 1 sense Webster, 1913 Aching /āk'-ĭng/ · Ach·ing · IPA /ˈeɪ.kɪŋ/ 01 a. That aches; continuously painful. See Ache. 1. That aches; continuously painful. See Ache. See: Ache “The aching heart, the aching head.” — Longfellow.