無数
むすう · musuu · JLPT N2 · na-adj
countless number
⭐ 無 = without, 数 = number: without a number, so countless
無 means none or without, and 数 means number. Together they mean a number you cannot count, so countless or infinite.
数 — 婁 (lóu, phonetic) + 攵 (action radical)
数 is a phono-semantic compound. The right side 攵 (a hand holding a stick) suggests an action, originally tallying or counting by striking marks. The left side 婁 supplies the sound. Over time the meaning broadened from 'to count' to 'number' and 'several'.