definition of
compression

[1] #1 compression n. [compaction, concretion, densification] an increase in the density of something. wn

[2] #2 compression n. [condensation, contraction] the process or result of becoming smaller or pressed together; "the contraction of a gas on cooling". wn

[3] #3 compression n. encoding information while reducing the bandwidth or bits required. wn

[4] #4 compression n. [compressing] applying pressure. wn