jähtyä

Jäähtyä is a Finnish intransitive verb meaning "to cool down" or "to become cold." It describes the process by which a substance loses heat and its temperature decreases as it approaches the surrounding environment. The term is commonly used for liquids, foods, metals, and air. It is distinct from jäätyä, which means to freeze and become solid.

Jäähtyä takes no direct object and agrees with its subject in person and number. The present tense is jäähtyy, the past tense jäähtyi, and the present perfect is on jäähtynyt. The infinitive is jäähtyä, and the past participle is jäähtynyt, used in compound tenses. The noun form jäähtyminen denotes the cooling process. In everyday language, it often describes natural cooling after heating, such as coffee or water left to cool.

Etymology: the verb is formed with the root related to jää, meaning ice or cold, plus the inchoative suffix -htyä, which signals a change of state. This construction is used in Finnish to express a transition into a cooler state, as opposed to jäätyä, which denotes freezing.

See also: jäähtyminen, jäähtyä and jäätyä are related terms in the Finnish lexicon for state changes of temperature. In scientific contexts, jäähtyminen is often discussed alongside heat transfer concepts such as conduction and convection, which describe how heat loss leads to cooling of a substance.