Open English Wordnet
Adjectives
(a)persistent, lastingretained; not shed“persistent leaves remain attached past maturity”, “the persistent gills of fishes”
(s)haunting, persistentcontinually recurring to the mind“haunting memories”, “the cathedral organ and the distant voices have a haunting beauty” (Claudia Cassidy)
(s)dogged, dour, persistent, pertinacious, tenacious, unyieldingstubbornly unyielding“dogged persistence”, “dour determination”, “the most vocal and pertinacious of all the critics”, “a mind not gifted to discover truth but tenacious to hold it” (T.S.Eliot), “men tenacious of opinion”