1540s, "binding, contracting," from Latin astringentum (nominative astringens), present participle of astringere "to bind fast, tighten, contract," from assimilated form of ad "to" (see ad-) + stringere "draw tight" (see strain (v.)). Related: Astringently; astringency. As a noun from 1620s, "an astringent substance, something which contracts tissues and thereby checks discharge of blood."