Tmesis
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In its strictest sense, tmesis (/ˈtmiːsɪs, təˈmiː-/; plural tmeses /ˈtmiːsiːs, təˈmiː-/; Ancient Greek: τμῆσις tmēsis – "a cutting" < τέμνω temnō, "I cut") is the dividing of a word into two parts, with another word inserted between those parts, thus forming a compound word. Example: "un-freaking-believable" (an emphatic way to say "unbelievable"). In a broader sense, tmesis is a set phrase, such as a phrasal verb, with one or more words interpolated within, thus creating a separate phrase.