14 possible answers to
Answers with 4 characters: CALM COOL EVEN Answers with 5 characters: QUIET STAID Answers with 6 characters: PLACID SEDATE SERENE SMOOTH Answers with 8 characters: TRANQUIL Answers with 9 characters: COLLECTED Answers with 10 characters: NONCHALANT PHLEGMATIC Answers with 15 characters: COOLASACUCUMBER