Synonyms of perennial

1 Syllable
plant, old
2 Syllables
weekly, yearlong, flowers, flower, undying, long-term, diurnal, annual, monthly, hourly, yearly, deathless, termless, constant, biennial, seedling, chronic, lasting, longterm
3 Syllables
durable, ceaseless, persistent, continuing, perpetual, orbital, sustained, unended, livelong, lingering, eternal, longstanding, unchanging, hardcore, unfailing, perennials, continual, timeless, periodic, immortal, recurrent, greenery, centennial, perduring, long-lived, long-lasting, abiding, lifelong, seasonal, permanent, incessant, unceasing
4 Syllables
sempiternal, never-ending, everlasting, never-ceasing, phoenixlike, perdurable, ever-present, unabating
5 Syllables
inveterate, imperishable, uninterrupted
6 Syllables
on-again-off-again