Medium loudness. Querying the information on Guoyin.com shows that the MF music symbol is the abbreviation of "mezzo forte", which means medium loudness. In music notation, f means strong, ff means stronger, and mf means slightly weaker than f and is described as "medium loudness." Music symbols are symbols or marks used to represent musical melody, rhythm, pitch, duration and other information. Music symbols can be divided into two major categories, namely rhythm symbols and pitch symbols.