Definition
To remove water vapor from the air, typically by cooling the air below its dew point so the moisture condenses out, or by passing it through a material that absorbs moisture.
Plain English
To take the moisture out of the air, making it drier.
Context Anchor
Seen in aircraft heating, ventilation, air conditioning, defogging, and equipment-storage discussions.
Derivation
From the Latin prefix 'de-' meaning 'remove' or 'reverse,' combined with 'humidify,' which comes from the Latin 'humidus' meaning 'moist.' So 'dehumidify' literally means 'to remove moisture.'
Why Pilots Care
Moisture promotes corrosion of metal parts and failure of avionics and electrical systems.
Intuition Check
Dehumidify does not simply mean “cool the air.” It means “remove moisture from the air,” even though cooling is one common way to do that.
Example Sentence 1
The air conditioning system both cools and dehumidifies the cabin air during flight.
Example Sentence 2
To protect the avionics, the owner chose to dehumidify the equipment bay during the winter months.