What is forcing or forced; -- a direction placed over a note, to signify that it must be executed with peculiar emphasis and force; -- marked fz (an abbreviation of forzando), sf, sfz, or called?

sforzando — Forcing or forced; -- a direction placed over a note, to signify that it must be executed with peculiar emphasis and force; -- marked fz (an abbreviation of forzando), sf, sfz, or. (Webster's 1913.)