活動
かつどう · katsudou · JLPT N3 · noun
activity
活動 = lively 活 + move 動: being alive and moving is activity
活 (katsu) means alive or lively, as in 生活 seikatsu, daily life. 動 (dou) means move, as in 動物 doubutsu, animal: a thing that moves. Lively movement gives activity, and it covers club activities and volcanic activity alike.
活 — water radical 氵 + tongue 舌
Originally a phono-semantic compound: 氵 (water) suggests flowing or liveliness, while 舌 (tongue) hints at the sound. Early forms depicted gushing water, conveying the idea of being lively or alive. The meaning broadened from 'flowing water' to 'living, alive, active.'