打ち消す
うちけす · uchikesu · JLPT N2 · verb-godan
to negate
打ち消す = strike (打つ) + erase (消す): strike a claim out
打つ means to hit or strike, and 消す means to erase or put out. When you deny something, you knock the statement down and wipe it away. The same 消 appears in 消しゴム (eraser).
打 — hand radical 扌 + nail 丁
打 combines the hand radical 扌 (action with the hand) with 丁 (originally a nail), suggesting striking or hitting with the hand. 丁 also serves as a phonetic hint in older readings. The meaning broadened from 'to strike' to a general verb for many hand-based actions, like 打电话 'make a phone call'.
消 — water 氵 + 肖 (phonetic)
消 is a semantic-phonetic compound: the water radical 氵 indicates the meaning, while 肖 (xiào) supplies the sound. It originally described water dwindling or melting away, and from there extended to the modern senses of vanishing, dissolving, and dispelling.