押さえる
おさえる · osaeru · JLPT N2 · verb-ichidan
to pin down
📌 押 is the push kanji of 押す (osu): osa-eru = push and keep it pressed
押さえる shares 押 and the osa- sound with 押す, to push. 押す is a single shove, while 押さえる means you push and keep pushing, so the thing stays held down or pinned in place, the way a pushpin holds paper to a board.
押 — hand radical 扌 + 甲 (jiǎ, phonetic)
押 is a semantic-phonetic compound. The hand radical 扌 supplies the meaning of pressing or holding down with the hand, while 甲 gives the sound. From the literal sense of pressing, it extended to signing/sealing documents, mortgaging, and detaining — all involving an authoritative 'pressing' action.