spare moment; free minute; moment's leisure
Rare term for a short period of free time. In modern Japanese, 暇 (ひま) or 空き時間 (あきじかん) are far more common.
Whenever I find a spare moment, I enjoy reading.
Compound of 小 (small, little) and 暇 (free time, leisure). The exact origin is uncertain, but it follows a common pattern of forming nouns meaning 'a little bit of X'.