persistent

adjectives

never-ceasing
"the relentless beat of the drums"
persistent, relentless, unrelenting
is derived from
persistency
is derived from
persistence
is derived from
persist
continually recurring to the mind
"haunting memories"; "the cathedral organ and the distant voices have a haunting beauty"- Claudia Cassidy
haunting, persistent
retained; not shed
"persistent leaves remain attached past maturity"; "the persistent gills of fishes"
lasting, persistent
is derived from
persist
is derived from
persist
antonym
caducous
stubbornly 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"
dogged, dour, persistent, pertinacious, tenacious, unyielding
is derived from
persistence