PERNICIOUS /pəˈnɪʃəs/ ► audio Scrabble 14 Words With Friends 18 Definition adjective exceedingly harmful. — synonyms: baneful, deadly, pestilent adjective working or spreading in a hidden and usually injurious way. — synonyms: insidious, subtle See all 508 words you can make from PERNICIOUS → 10-letter words Words starting with P Words ending with S ← Unscramble different letters