Floating tone
A floating tone is a morpheme or element of a morpheme that contains no consonants, no vowels, but only tone. It cannot be pronounced by itself, but affects the tones of neighboring morphemes.
An example occurs in Bambara. Bambara has two phonemic tones, high and low. In this language, the definite article is a floating low tone. With a noun in isolation, it is associated with the preceding vowel, turning a high tone into a falling tone: [bá] river; [bâ] the river. When it occurs between two high tones, it downsteps the following tone: