CYST /sɪst/ ► audio Scrabble 9 Words With Friends 9 Definition noun a closed sac that develops abnormally in some body structure. noun a small anatomically normal sac or bladderlike structure (especially one containing fluid). — synonyms: vesicle See all 2 words you can make from CYST → 4-letter words Words starting with C Words ending with T ← Unscramble different letters