"Moister" Natural Recordings by Native Speakers
The word "moister" is not as commonly used as its counterpart "moist", but it is an adjective that means "having more moisture" or "more humid". For example, "The air in the room was moister than usual, making it feel more oppressive."
A moistener is a substance or device that adds or retains moisture to something, typically to prevent drying out or to facilitate a specific process. This can include sprays, lotions, creams, or other topical applications used in various industries such as agriculture, manufacturing, or beauty and cosmetics.
Moistening is the act of making something wet or humid, typically by adding water or another liquid. It is often used to describe the process of humidifying or dampening something, such as the air, a surface, or an object. For example, "The gardener moistened the soil to prepare it for planting."