noun
Etymology: translation of Late Latin spiritus asper
1. : a mark ʽ used in Greek over some initial vowels or over ρ to show that they are aspirated (as in ὡς pronounced ˈhōs or ῥη̃τωρ pronounced ˈhrātōr)
2. : the sound indicated by a mark ʽ over a Greek vowel or ρ — called also spiritus asper ; compare breathing 2, smooth breathing