compact

Pluralcompacts

Formscompacts, compacting, compacted

1. 1
   adjective

   Having all the necessary features arranged neatly in a small space.

   The hotel room was compact but still had a desk, a sofa bed, and a tiny kitchen.

   She bought a compact camera that slips easily into a jacket pocket.

   Similarsmall, snug, portable

   Oppositebulky, spacious, roomy

2. 2
   adjective

   Closely packed or dense, with a lot of material in a small volume.

   Clay soil is so compact that rainwater struggles to drain through it.

   The loaf had a compact, heavy crumb with almost no air holes.

   Similardense, crowded, concentrated

   Oppositeloose, porous, airy

   Note

   Packing is built into the word: Latin compactus meant "joined together," from com-, "together," and a verb meaning "to fasten." Isaac Newton's Opticks (1704) groups glass, crystal and gems as compact bodies, solid all the way through. For the comparative, both more compact and compacter exist, and the superlative likewise has two forms.

3. 3
   nouncountable

   A car larger than a subcompact but smaller than an intermediate model.

   A compact is far easier to squeeze into a tight city parking space than a full-size SUV.

   The rental agency had run out of compacts, so they gave us a midsize sedan at the same price.

4. 4
   verbtransitive

   To press something together so that it becomes denser.

   Roll the gravel several times to compact it before laying the paving stones.

   Heavy trucks compact the soil and make it harder for roots to grow.

   Similarcompress, pack, tamp, consolidate

   Oppositeloosen

5. 5
   nouncountable

   A thin folding case small enough for a woman's purse, handbag, or pocket, often holding a mirror, face powder, and a puff.

   She snapped open her compact and dabbed powder on her nose before the meeting.

   Collectors pay high prices for antique enameled compacts with their original puffs.

6. 6
   nouncountable

   An agreement or contract between two or more parties.

   The neighboring states signed a compact to share water from the river.

   Many voters felt the government had broken the social compact with working families.

   Similaragreement, pact, contract, treaty

   Note

   This compact reached English from Latin compactum, "agreement," separately from the compact of tight packing, which goes back to a verb for joining together. Its company today is public life: a social compact between a government and its people, a compact between neighboring states, a "crypto compact" that the U.S. Conference of Mayors was urged to sign in 2022.

7. 7
   adjective

   Of prose, brief and full of meaning, with no wasted words.

   Her compact prose packs a great deal of feeling into a few short chapters.

   The summary is admirably compact, covering every main finding in a single page.

   Similarconcise, succinct, terse, pithy, economical

   Oppositeverbose, wordy, rambling, diffuse

8. 8
   nouncountable

   A broadsheet newspaper printed at tabloid size that keeps its serious, non-sensational style.

   The paper dropped its broadsheet format last year and now appears as a compact.

   Commuters said the new compact was much easier to read on a crowded train.

   Note

   The label lets a serious paper take the tabloid's size without the tabloid's name, which suggests sensation. When the Dundee Courier announced in 2012 that it would relaunch as a compact, its editor promised a "brighter, bolder" paper, "shrunk from broadsheet to tabloid size." Papers relaunch as a compact or move to compact, the second use treating the word as a format.

9. 9
   verbintransitive

   To make an agreement or contract with others.

   Rival companies that compact to fix prices are breaking the law.

   The two families compacted to divide the land equally between their heirs.

   Similaragree, contract

10. 10
    verbtransitive

    To unite or connect parts firmly into a single whole, as in a system.

    The new constitution compacted a loose alliance of colonies into one federal union.

    Shared hardship can compact a group of strangers into a loyal crew.

    Similarunite, unify, consolidate, weld, forge

    Oppositedivide, split

    Note

    Here the verb stays closest to its Latin sense of joining together, and the King James Bible of 1611 pairs the two: the whole body "fitly joined together and compacted." It describes parts locked into one working whole, a body, a federation, a crew, rather than matter pressed denser, which is the compressing sense.

11. 11
    adjective

    Of a topological space, having a finite subcover for every open cover; in a metric space, equivalent to being sequentially compact, and with the Heine-Borel property, to being closed and bounded.

    The closed interval from 0 to 1 is compact, but the open interval is not.

    A closed subset of a compact space is itself compact.

    Note

    Topologists treat compactness as the next best thing to finiteness. In familiar settings it wears friendlier faces, sequential compactness in a metric space and closed and bounded where the Heine-Borel property holds, which is why the closed interval from 0 to 1 is compact and the open one is not. The adjective does not compare: a space is compact or it is not.

12. 12
    adjective

    Of a topological space, having a finite subcover for every open cover and also being Hausdorff, with any two distinct points separable by disjoint open sets.

    Every compact space is normal, so Urysohn's lemma applies to it directly.

    The Zariski topology on a curve is quasi-compact but not compact, because it is not Hausdorff.

    Note

    Under this stricter convention the Hausdorff condition is part of the word, and the bare open-cover property is called quasi-compact instead. Readers have to check which convention a text follows: a claim such as every compact space is normal holds here but fails under the looser meaning, and the Zariski topology on a curve is quasi-compact without being compact.

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