tuplaantuu

Tuplaantuu is a Finnish verb meaning “to become double” or “to double.” It is the third-person singular present indicative form of the intransitive verb tuplaantua, used to describe a process in which a quantity or value increases to twice its previous level.

Etymology and form: The stem tupla means “double,” and the suffix -antua marks a process or change of state, yielding verbs such as tuplaantua (to become double) and tuplaantuu (it becomes double). Related nouns include tupla (double) and tuplaantuminen (the act or process of doubling). Grammatical notes: tuplaantuu is intransitive; its subject is the entity that doubles. The past tense is tuplaantui, and the past participle is tuplaantunut.

Usage: The term is used across economics, demography, ecology, and general descriptive language to indicate that a quantity or value has doubled. It is commonly paired with a time frame, for example, “hinta tuplaantuu muutamassa vuodessa” (the price doubles in a few years) or “väestö tuplaantuu 50 vuodessa” (the population doubles in 50 years). In discussions of growth, “tuplaantuminen” may be used as a noun to refer to the act of doubling.

See also: tupla, tuplaantuminen, kaksinkertaistuminen.