出典:Wiktionary
The noun is derived from left (adjective) + turn (noun).[1]
The interjection is derived from left (adverb) + turn (verb), while the verb is derived from the interjection.[2]
left turn (三人称単数 現在形 left turns, 現在分詞 left turning, 過去形および過去分詞形 left turned)