入院
にゅういんする · nyuuinsuru · JLPT N4 · noun
hospitalization
🏥🛏️ 入院 = enter (入) + institution (院): going into hospital
入 means enter, and 院 is the institution in 病院 (byouin, hospital). Enter the 院 and you are hospitalized. The opposite swaps one kanji: 退院 (taiin) = retreat from the institution, i.e. discharge. Add する to make it a verb.
入 — single pictograph, two slanting strokes
入 is a pictograph showing an arrowhead or pointed entrance, with two strokes converging downward to suggest something going inward. The original sense was 'to enter,' and it still carries that meaning today. It contrasts visually with 人 (person), where the strokes cross differently at the top.
院 — left ear 阝(阜) + complete 完
院 is a semantic-phonetic compound. The left 阝 (from 阜, mound/hill) suggests walls or enclosed terrain, hinting at an enclosed space. The right 完 (wán) provides the sound and originally meant 'complete', so 院 came to mean a walled courtyard or institution like a hospital or academy.