当てはめる
あてはめる · atehameru · JLPT N2 · verb-ichidan
to apply
🧩 当てる (put against) + はめる (fit in) = press it on so it fits
当てる means to put something against a target, and はめる means to fit something into a slot, like a puzzle piece. Together they mean applying a rule or pattern to a case so it fits.
当 — small ⺌ + crown 冖 + hand 彐 (simplified from 當: 尚 + 田)
Originally written 當, combining 田 'field' with 尚 as a phonetic. The early sense was 'to match' or 'face' a field of equal value, extended to 'correspond to', 'ought to', and 'serve as'. The simplified form 当 streamlines the upper 尚 component.