An astringent (sometimes called adstringent) is a chemical that shrinks or constricts body tissues. The word derives from the Latin adstringere, which means "to bind fast". Calamine lotion, witch hazel, and yerba mansa, a Californian plant, are astringents, as are the powdered leaves of the myrtle.

Astringency, the dry, puckering or numbing mouthfeel caused by the tannins in unripe fruits, lets the fruit mature by deterring eating. Ripe fruits and fruit parts including blackthorn (sloe berries), Aronia chokeberry, chokecherry, bird cherry, rhubarb, quince and persimmon fruits (especially those which are unripe), banana skins (or unripe bananas), cashew fruits and acorns are astringent. Citrus fruits, like lemons, are somewhat astringent. Tannins, being a kind of polyphenol, bind salivary proteins and make them precipitate and aggregate, producing a rough, "sandpapery", or dry sensation in the mouth. The tannins in some teas, coffee, and red grape wines like Cabernet Sauvignon and Merlot produce mild astringency.

Squirrels, wild boars, and insects can eat astringent food as their tongues are able to handle the taste.

In Ayurveda, astringent is the sixth taste (after sweet, sour, salty, pungent, bitter) represented by "air and earth".

Smoking tobacco is also reported to have an astringent effect.

In a scientific study, the sensation of astringency was still able to be felt by subjects who had local anesthesia applied to their taste nerves, but not when both these and the trigeminal nerves were disabled.