WordNet sense 1 (resistant to change of position or condition):

stable

WordNet sense 2 (retained; not shed):

persistent

WordNet sense 3 (continuing forever or indefinitely):

eternal, everlasting, perpetual, unending

WordNet sense 4 (unceasing):

abiding, enduring

WordNet sense 5 (continuing or enduring without marked change in status or condition or place):

permanent

WordNet sense 6 (existing for a long time):

durable, long-lasting, long-lived