Middle English, from Old English brōc; akin to Old High German bruoh marshy groundMiddle English brouken, broken "to have the benefit of, enjoy, employ, use, eat or drink, stomach, tolerate," going back to Old English brūcan "to enjoy the use of, use, employ, partake (of food or drink), possess," going back to Germanic *brūkan-/*brūkjan- (whence also Old Frisian brūka "to make use of, employ," Old Saxon brūkan "to enjoy the use of," Middle Dutch brūken "to use, enjoy," Old High German brūchan "to enjoy the use of," Gothic brūhjan "to use"), going back to dialectal Indo-European *b^hruHg- "enjoy, use" whence also Latin fruor, fruī "to enjoy the produce or proceeds of, derive advantage from, be blessed with, derive pleasure from" (see fruit entry 1)

NOTE: The Indo-European etymon *b^hruHg- is attested only in Germanic and Italic, and within Germanic not in the northern branch (Danish bruge "to use," Swedish bruka, etc., are loans from Low German). In Old English brūcan is a Class II strong verb (preterit breac, brucon, participle brocen), and in Old Saxon brūkan, attested only in the infinitive, is probably also strong. In Middle English and the other Germanic languages, however, it is a weak verb, with only traces of possible strong forms. The phonetic outcome displayed by Modern English brook, with [u], is peculiar and cannot directly continue Old English ū. E. J. Dobson hypothesizes that a new Middle English infinitive with ŭ was formed on the analogy of the weak past tense and past participle early enough to undergo open-syllable lengthening—hence brŭken > brọ̄ken > brook, with [u:] later shortened to [u] (see English Pronunciation, 1500-1700, 2. edition, Oxford, 1968, p. 513). Present-day English continues only a small portion of the original meaning of the verb.