Semantically idiosyncratic MWEs, or idiomatic expressions, are non-compositional in that their meanings cannot be predicted from their parts; these expressions are used frequently to make language more fluent (Jackendoff, 1997), and often contain word senses not found in other contexts.
identifying non-compositional MWEs presents a clear challenge for fields such as automatic machine translation (MT), information retrieval, natural language understanding, natural language generation, question answering, text summarisation, and word sense disambiguation (McCarthy et al., 2007).