General term for a dark or black spot on a surface, such as a stain, blemish, or marking.
There is a black spot on the wall.
sunspot
Astronomical term for a temporary dark patch on the sun's surface.
Sunspots increase and decrease in an approximately 11-year cycle.
Compound of 黒 (koku, 'black') and 点 (ten, 'point, spot'). The reading is on'yomi.