Ⱬ (minuscule: ⱬ, Unicode codepoints U+2C6B and U+2C6C, respectively) is a Latin letter Z with a descender.
It is used in pre-1983 romanization of the Uyghur language, transliterating ژ [ʒ], a pre-consonantal allophone of ج /dʒ/ (see Qona Yëziq), but occurring independently in a few words of Russian, Persian or Western origin (such as ⱬurnal from journal). It corresponds to the digraph zh in the current ULY standard.
Also, Z with descender was used in 1932—1936 Latin orthography for the Komi language. It represented a voiced alveolo-palatal sibilant [ʑ].
References
Z with descender Wikipedia(Text) CC BY-SA