Adynaton is an extravagant form of hyperbole in which the speaker imagines something physically or logically impossible, such as rivers running backward or the stars being counted, to convey overwhelming emotion or certainty. The impossibility is not meant to deceive; it gives an idea a scale beyond ordinary statement. In poetry, adynaton appears in love complaints, vows, laments, prophecies, and comic exaggeration. Poets use it to dramatize desire, grief, loyalty, or despair, turning an inward feeling into an image of cosmic or natural disruption.

Adynaton pushes hyperbole beyond probability into impossibility, as when a speaker says the sea will dry before grief ends. Its force depends on the audience recognizing the impossibility. In poetry, it often conveys vows, love, rage, or despair; compare ordinary hyperbole, which need not describe an impossible event.