Synonyms for Persistent (same or very similar meaning)
WordNet sense 1 (retained; not shed):
lasting
WordNet sense 2 (continually recurring to the mind):
haunting
WordNet sense 3 (impossible to forget):
unforgettable
WordNet sense 4 (never-ceasing):
relentless, unrelenting
WordNet sense 5 (seemingly without interruption; chiefly restricted to what recurs regularly or frequently in a prolonged and closely spaced series):
continual
From the ODE community, based on WordNet
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