注射
ちゅうしゃ · chuusha · JLPT N4 · noun
injection
💉 注射 = pour (注) + shoot (射): liquid shot into the body
注 means to pour, as in 注ぐ and 注文. 射 means to shoot, as in 発射 (launch). An injection is liquid poured in by shooting it through a needle. Careful: 駐車 (parking) is also read ちゅうしゃ, so the kanji tell them apart.
注 — water 氵 + master 主 (phonetic)
A semantic-phonetic compound: 氵 (water) gives the meaning of pouring or flowing, while 主 supplies the sound. The original sense was 'to pour water in,' which extended to 'concentrate, focus' (as in pouring attention) and 'to annotate' (pouring explanation into a text).
射 — body 身 + inch/hand 寸
Originally a pictograph of a hand drawing a bow with an arrow. The ancient form showed 弓 (bow) plus 矢 (arrow) or a hand. Over time it was reshaped into 身 (body) plus 寸 (hand/measure), and the meaning 'to shoot' was extended to 'emit' or 'project'.