To press or squeeze something so that it becomes smaller or more compact. She used a machine to compress the cardboard boxes for recycling.
To reduce the size of a file or data by encoding it more efficiently. The software can compress large video files without losing quality.
To condense or shorten a piece of writing or speech. The editor had to compress the article to fit the word limit.
To become smaller or more compact as a result of pressure; to be compressed. The sponge compresses when you squeeze it.