indescribable (adj.)

• exceptional
• extraordinary
• fabulous
• indefinable
• ineffable
• inexpressible
• legendary
• marvelous
• mythical
• noncommunicable
• noteworthy
• phenomenal
• portentous
• prodigious
• remarkable
• stupefying
• stupendous
• undefinable
• unexampled
• unmentionable
• unnameable
• unparalleled
• unprecedented
• unspeakable
• untellable
• unutterable
• wonderful