温室
おんしつ · onshitsu · JLPT N2 · noun
greenhouse
🌱 温 = warm + 室 = room: a warm room for growing plants
室 (shitsu) means room, as in 教室 (kyoushitsu, classroom). 温 (on) means warm, as in 温度 (ondo, temperature). Put them together for a warm room.
室 — roof 宀 + arrive 至
A semantic compound: 宀 (roof/house) over 至 (to arrive). The image is a place one arrives at and stays in — an inner room. From 'inner chamber' the meaning broadened to 'room' generally, and by extension to specialized rooms like an office or laboratory.