Dew was an accumulation of water droplets on the ground caused by condensation.
In 2256, Sylvia Tilly considered that Paul Stamets' skin looking "dewy" was a sign the sporal therapy used to treat his coma was working. (DIS: "Vaulting Ambition")
In 2269, Doctor Leonard McCoy referred to the Phylosian antidote for the bite of the Retlaw plant as an "alien dew drop". (TAS: "The Infinite Vulcan")