Ambisyllabic

A segment is ambisyllabic if it belongs to two syllables.

Example
The English word hammer cannot be divided into two syllables ha and mer; the [m] functions both as the final segment of the first syllable and as the initial consonant of the second syllable.

Link
Utrecht Lexicon of Linguistics

Reference
Kahn, Margaret 1976. Borrowing and variation in a phonological description of Kurdish. Diss. Ann Arbor, Univ. of Michigan.