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compress

/kəmˈpres/·verb

to press something into less space; to squeeze together
Fig. 1 — The recycling baler takes a chamber full of loose cardboard — a heap taller than a person, mostly air and angles.
01Definition

To compress is to press something together until it takes up less room. Nothing is removed — the cardboard in the baler, the air in the cylinder and the data in the zip file all survive complete — but the empty space between the parts is forced out, and what remains is denser, tighter, harder. From Latin com- 'together' plus premere 'to press'. The word reaches wherever room is scarce: engineers compress air, editors compress chapters, planners compress a five-year programme into three.

02In use
  • iThe baler compresses loose cardboard into dense, strap-bound blocks.
  • iiThe negotiators agreed to compress the timetable so the treaty could be signed before the election.
  • iiiA gas will expand to fill its container and compress again under the weight of a piston.
03Collocations
  • compressed air
  • compress a file
  • compress the schedule
  • tightly compressed
  • compress a spring

Family compression (noun) · compressed (adjective) · compressor (noun)

04Relations

=squeeze, compact, condense, constrict, cram

≠expand, decompress, loosen

06TOEFL & IELTS

A physics-and-planning verb both exams lean on. In TOEFL science passages gases compress and expand, rock layers are compressed into strata, and compression explains everything from engines to earthquakes. In IELTS writing, compressing a schedule, a budget or an argument signals precision. Mind the stress: the verb is com-PRESS, while the noun — a cold COM-press, the pad pressed to an injury — moves the stress forward; recognise it in reading. Compression is the workhorse noun for process essays: data compression, compression of the timetable.

07Asked
Where is the stress in compress — is it COM-press or com-PRESS?
Both, and the stress is the meaning. The verb is com-PRESS: you comPRESS a file, a spring, a schedule. The noun is COM-press: a COMpress is the folded pad pressed against an injury. English does this verb/noun stress shift systematically (reCORD/REcord, perMIT/PERmit), and compress is one of the cleanest examples examiners can hear.
What is a cold compress?
A pad — folded cloth, gauze, or a wrapped ice pack — pressed against an injury or ache. The cold narrows blood vessels near the surface, which helps swelling subside and dulls pain; a warm compress does the opposite, easing stiff muscles by widening them. First-aid instructions in reading passages use the noun freely, so recognise the front-stressed COM-press on sight.
What is the difference between compress and condense?
Compress is outside force: a piston, a plate or an algorithm squeezes something into less room, as the baler in the scene above squeezes the air out of a heap of cardboard. Condense is a settling into denser form — vapour condenses into drops, a report condenses into a brief. Both can shorten a text, but compress emphasises the squeeze, condense the denser result.
What does compressing a file actually do?
It rewrites the data to spend fewer bits on repetition — a pattern that appears a hundred times is stored once plus instructions. Lossless compression (zip files) keeps every bit recoverable; lossy compression (JPEG images, MP3 audio) also throws away detail the eye or ear barely misses, which is why heavily compressed photos look smudged.
What does it mean to compress a schedule or timetable?
To fit the same work into less time — deadlines move closer together, stages overlap, and nothing is officially dropped. Project managers speak of compressing the schedule when a launch date will not move; universities compress a semester into a summer term. The implication is strain: a compressed timetable, like compressed air, holds pressure.
Is decompress the opposite of compress?
Yes, in every register. Files are decompressed (unzipped) back to full size; divers decompress by surfacing in stages so dissolved gas leaves the blood safely; and informally, people decompress after stress — let the pressure off. The prefix does honest work in all three: whatever was squeezed is allowed to take up its room again.