温泉
おんせん · onsen · JLPT N2 · noun
watering place
♨️ 温 = warm, 泉 = spring: a warm spring of water, which is what 'onsen' means
温 (on) means warm and 泉 (sen) means spring or fountain. Together they name a hot spring, the same word used for Japanese bathhouses fed by one.
泉 — white 白 above water 水
泉 is a pictograph showing a spring: water (水) flowing out from an opening in a rock, with 白 on top representing the mouth of the spring. The original oracle bone form depicted water streaming from a hollow. Its core meaning, 'spring' or 'fountain,' has remained stable since ancient times.