整数
せいすう · seisuu · JLPT N2 · noun
integer
整 (whole, complete) + 数 (number) = whole numbers, including negatives and zero
整 means whole or complete, and 数 means number. Integers are whole numbers: ..., -2, -1, 0, 1, 2, ... with no fractional parts.
整 — 束 bundle + 攵 tap/strike + 正 correct/upright
A compound character combining 敕 (to arrange, with 束 'bundle' and 攵 'strike/action') over 正 ('upright, correct'). The image is of striking a bundle into proper alignment, giving the meaning 'to put in order, arrange neatly.' From this came senses of 'whole, complete, tidy.'
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'.