noun. any of various complex phenolic substances of plant origin; used in tanning and in medicine.
Example sentences of the word tannin
1. Noun, singular or mass
This mixture will react with the tannin to turn the items black and act as a mordant to fix the colour in the items you are dying.
2. Noun, plural
However, you need to treat them before roasting, since they contain tannin, which is slightly bitter.
Most of the tannins are found in the skin of fruits and fruits that aren't as ripe, so choosing very ripe fruit and avoiding the skin can help you limit your tannin intake.