Lexical phrases are combinations of fixed words that behave like single words and include collocations, phrasal verbs, idioms, social formulae, and binominals. Collocations are words that always appear together and convey meaning by association. Phrasal verbs combine a verb and particle to form a single semantic and syntactic unit. Idioms have meanings different from their individual words. Social formulae are fixed exchanges used in social situations. Binominals refer to pairs or groupings of words often used together through repetition, antonyms, synonyms, or alliteration.