normal temperature; room temperature
Refers to the ambient temperature of the surrounding environment, typically around 20–25°C. Common in instructions for food, medicine, and chemical storage.
この薬は常温で保存してください。
Please store this medicine at room temperature.
Please store this medicine at room temperature.
常温の水で飲んでください。
Please take it with water at room temperature.
constant temperature; fixed temperature
Used in scientific or technical contexts to mean a temperature that is kept steady, as in a thermostatic chamber or incubator.
実験では常温を保つ必要がある。
In the experiment, it is necessary to maintain a constant temperature.
バターは使う前に常温に戻しておく。
Let the butter come back to room temperature before using it.
It's dangerous to leave raw meat sitting out at room temperature.
恒温 explicitly means a temperature kept constant by artificial control (e.g. in an incubator), whereas 常温 in this technical sense just means a steady ambient level without implying active regulation.
冷蔵 means refrigerated storage at a low temperature, contrasting with 常温 which means storing something at ordinary, unrefrigerated temperature.
冷凍 means storing something frozen, the more extreme opposite of 常温's ordinary, unchilled temperature.
Compound of 常 (じょう, 'normal, usual') and 温 (おん, 'temperature'). The reading is on'yomi, and the word is a straightforward Sino-Japanese coinage.