Lissome:
attractively thin and able to move quickly and smoothly [Cambridge Dictionary]
Somehow I’ve never known the definition. Noted in “Prince Philip, royal consort to Queen Elizabeth II, dies at 99,” Adrian Higgins, WaPo:
During a visit to the naval college by the royal family, less than two months before the outbreak of World War II, Philip, then 18, entertained Princess Elizabeth, who was just 13 and was soon smitten by the lissome, blue-eyed cadet.
