De-humidifying refers to the process of removing moisture from the air. The antonyms, or opposite meanings, for this word would be humidifying or moistening. These words refer to the act of increasing the amount of moisture in the air, which can be beneficial for certain environments such as indoor plants or for those with dry skin. When humidifying a room, Adding a humidifier can help add moisture to the air, which can reduce the risk of dry skin, allergies, and other respiratory issues. In contrast, de-humidifying can be useful for areas that are prone to excess moisture, which can lead to mold or mildew growth.