Fleeting stains that temporarily "cover" or accompany mental activity (more precisely, clear light mental activity), thereby preventing the mental activity from cognizing phenomena without accompanying disturbing emotions or attitudes. They include the disturbing emotions and attitudes, as well as their tendencies (seeds), and prevent the attainment of liberation from samsara.
Tibetan: ཉོན་སྒྲིབ། nyon-sgrib
J. Hopkins: Afflictive obstruction
Synonyms: Obscurations that are disturbing emotions and attitudes; Obscurations preventing liberation