What is the meaning of ḿ?

a palatalized m sound (IPA [mʲ]).

A letter formerly used to represent the sound //, now replaced by the digraph mj.

Hanyu Pinyin reading of

Hanyu Pinyin reading of

The eleventh letter of the Yup'ik alphabet, written in the Latin script.

A syllabic letter m with high tone

Source: wiktionary.org