That which moistens or makes damp or wet; exuding fluid; liquid in small quantity.
"The morning dew added a refreshing layer of moisture to the dry grass."
In plain English: Moisture is water that exists as vapor, liquid, or dampness rather than ice or steam.
"The gardener checked the soil to make sure there was enough moisture for the plants to grow."
Usage: Moisture refers to the presence of water, such as humidity in the air or sweat on skin, rather than a specific amount of liquid. Use this word when describing general dampness instead of synonyms like "wetness" which implies being soaked through.
The word moisture comes from the Old French term moistour, which meant dampness or wetness. It entered English through Middle English with this same meaning.