Sorry you have never heard of the word. The many bright folks on TCS have often played words I have never heard of and I have had to look them up. Here is how a few online dictionaries define "dewy." Miriam Webster
Definition of dewy
dewier; dewiest
1: moist with, affected by, or suggestive of dew
dewy grass
A fresh, faintly dewy complexion radiates health and beauty.