Phrase, expression, idiom, locution all refer to grammatically related groups of words. A phrase is a sequence of two or more words that make up a grammatical construction, usually lacking a finite verb and hence not a complete clause or sentence: shady lane (a noun phrase); at the bottom (a prepositional phrase); very slowly (an adverbial phrase). In general use, phrase refers to any frequently repeated or memorable group of words, usually of less than sentence length or complexity: a case of feast or famine—to use the well-known phrase. Expression is the most general of these words and may refer to a word, a phrase, or even a sentence: prose filled with old-fashioned expressions. An idiom is a phrase or larger unit of expression that is peculiar to a single language or a variety of a language and whose meaning, often figurative, cannot easily be understood by combining the usual meanings of its individual parts, as to go for broke. Locution is a somewhat formal term for a word, a phrase, or an expression considered as peculiar to or characteristic of a regional or social dialect or considered as a sample of language rather than as a meaning-bearing item: a unique set of locutions heard only in the mountainous regions of the South.