tmesis

[tuh-mee-sis] /təˈmi sɪs/
noun
1.
the interpolation of one or more words between the parts of a compound word, as be thou ware for beware.
Origin
1580-90; < Late Latin tmēsis < Greek tmḗsis a cutting, equivalent to tmē- (variant stem of témnein to cut) + -sis -sis
Related forms
tmetic [tuh-met-ik] /təˈmɛt ɪk/ (Show IPA), adjective
British Dictionary definitions for tmesis

tmesis

/təˈmiːsɪs; ˈmiːsɪs/
noun
1.
interpolation of a word or group of words between the parts of a compound word
Word Origin
C16: via Latin from Greek, literally: a cutting, from temnein to cut
Word Origin and History for tmesis

1570s, from Greek tmesis "a cutting," related to temnein "to cut," tome "a cutting" (see tome). The separation of the elements of a compound word by the interposition of another word or words (e.g. a whole nother).