From Longman Dictionary of Contemporary Englishwillowywil‧low‧y /ˈwɪləʊi $ -loʊi/ adjective THIN PERSONtall, thin, and graceful She was pale and willowy, with violet eyes.
Examples from the Corpus
willowy• She need not be beautiful in the traditional sense of Anglo-Saxon beauty: tall, blond and willowy.• Anastasia was willowy and graceful, with grey eyes and long, straight red hair.• Clusters of tall, willowy bamboos rose out of ten pale-pink marble planters and almost touched the high triple-domed ceiling.• In contrast to Francesca, who was tall and willowy, Diana was small and curvy.• It consisted of a willowy double branch of a tree.• Outside, a fair, willowy girl and a heavy-set woman in white were walking across the lawn.• Her long willowy legs splayed outwards into a balletic second.• Blonde Patsy, who is eight months pregnant, looked a far cry from the willowy screen siren bedded by Mel Gibson.• She was pale and willowy, with a large mouth and the most amazing violet eyes that you ever did see.• Tania was tall and willowy with topaz eyes.• But not a willowy woman, rather an outright presence. 