quality -- (an essential and distinguishing attribute of something or someone; "the quality of mercy is not strained"--Shakespeare)
quality, caliber, calibre -- (a degree or grade of excellence or worth; "the quality of students has risen"; "an executive of low caliber")
quality, character, lineament -- (a characteristic property that defines the apparent individual nature of something; "each town has a quality all its own"; "the radical character of our demands")
timbre, timber, quality, tone -- ((music) the distinctive property of a complex sound (a voice or noise or musical sound); "the timbre of her soprano was rich and lovely"; "the muffled tones of the broken bell summoned them to meet")
quality -- (high social status; "a man of quality")