输血
shū xuè · HSK 7
to give aid and support
🩸 输 (transport) + 血 (blood) = move blood from one body into another
输 means to transport or deliver; 血 is blood. Together: deliver blood = transfuse. The figurative sense, to give aid and support, extends the same idea: pumping fresh blood into something that needs help.
输 — cart 車 + 兪 (phonetic)
输 is a phono-semantic compound. The radical 車 (cart/vehicle) gives the meaning, originally referring to transporting goods by cart. The component 兪 supplies the sound. From 'transport' it extended to 'send/deliver', then by metaphor to 'lose' (as in handing over stakes in a game).
血 — drop 丿 over dish 皿
Originally a pictograph of a sacrificial vessel (皿) with a drop of blood inside, marking the offering of blood in ancient rituals. The small stroke on top represents the blood itself. Over time it broadened from ritual blood to blood in general.