tranquilise Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition verb. to make or become tranquil; specif; to calm by the use of a tranquilizer Example Sentence They had to tranquilise the animal to capture it. British spelling. Synonyms calm; calm down; quiet; quieten; lull Antonyms excite Hear It! Say It! Write It! tranquilise Switch to cursive Start Share with your friends: