Compression/kəmˈpreʃn/ Definition 1 of 4Pro Tip 1/3Physical Process Compression means physically squeezing, often to fit something into a smaller space. Using compression, you can fit more clothes in your suitcase. Pro Tip 2/3Not Always Visible Compression doesn't just apply to solid objects; invisible gases and liquids can also be compressed. Divers use tanks with compressed air. Pro Tip 3/3Metaphorical Use Sometimes 'compression' is used in a non-physical sense, like squeezing words for a summary. I used compression to shorten my essay.