Since the linguistic units we aim to extract in this study are not restricted to any syntactic construction or semantic domain, we use the term FSs based on Schmitt (2010)'s suggestion of using this term as an umbrella one to refer to various types of linguistic units in general.
the current study adopts a practical definition of Arabic FSs which basically concentrates on any type of syntactic construction from different language domains that makes high frequency use of semantically regular phrases.