内科
ないか · naika · JLPT N2 · noun
clinic
🩺 内 = inside + 科 = department: the department for problems inside the body
Its pair is 外科 (geka, surgery). 外 means outside, so internal medicine handles inside problems and surgery handles outside ones.
内 — enclosure 冂 + enter 入
内 originally depicted something entering (入) into an enclosed space (冂), giving the core sense of 'inside' or 'within'. The pictographic image of going into a covered area extended naturally to meanings like inner, internal, and inland. It contrasts with 外 ('outside').
科 — grain 禾 + measure 斗
科 combines 禾 (grain) and 斗 (a dipper/measure), originally depicting the act of measuring or grading grain. From this, it extended to mean classification, category, and branch of study. Today it commonly appears in words for science (科学) and academic disciplines.