From Ottoman Turkish چابوق (çabuk), cognate with or derived from Persian چابک (čābok). Nişanyan suggests a Turkic origin for the Persian (cf. çapmak), but existence of older Iranian forms makes that doubtful. The word may have entered Turkic before the first written records of the language family. The Ottoman pronunciation چابك (çabük) is more clearly a Persian borrowing but the modern form has a back vowel (u or sometimes ı in 20th century writing).