Tmesis (Greek, "a cutting") is a figure of speech in which a word or phrase is inserted into another word, often for humorous effect. The insertion may occur between the parts of a compound word, of an infinitive (split infinitive), or between syllable boundaries (dystmesis ).

Also referred to as diacope , or tumbarumba; the latter due to the popularity of tmesis in Australian speech. Linguists sometimes describe tmesis as a form of infixing.

Examples:

• "what-place-soever"; note that "whatsoever" is itself an example of tmesis, being an insertion of "so" into "whatever"
• "I can't find it any-blooming-where" (see also expletive infixation)
• "how heinous e'er it be" (Shakespeare's tmesis of "however" in Richard II)
• "any-old-how" (parallel to "any old thing")
• Perhaps the most famous example of tmesis employed within a proper name is the popular American expression of surprise or frustration: "Jesus H. Christ" For many years the British have used the similar "Christ All-bleeding-mighty".