exact

Formsexacts, exacting, exacted

1. 1
   adjective

   Matching a fact, standard, or the truth in every detail, with nothing more or less.

   The architect demanded the exact measurements before any material was cut.

   His account of the crash matched the exact sequence of events on the recording.

   Similarprecise, accurate, correct, specific

   Oppositeapproximate, rough, inexact, imprecise

   Note

   The core sense, and the etymology still shows in it: Latin exāctus comes from exigō, "to measure by a standard, weigh, test," built from ex "out" and agō "drive." An exact thing has passed that test. It compares both ways, exacter and exactest or more exact and most exact. It pairs naturally with things that can be checked: exact time, an exact copy, exact accounts.

2. 2
   adjective

   Always careful to keep to a rule, standard, or promise, and so accurate, methodical, and punctual in what one does.

   The bookkeeper was exact in every entry, never leaving a penny unaccounted for.

   An exact and methodical worker, he double-checked each step before moving on.

   Similarmeticulous, precise, scrupulous, punctilious, careful

   Oppositecareless, sloppy, slapdash

   Note

   Here the precision belongs to a person's habits rather than to a measurement. The adjective takes in for what someone is careful about, as in a man exact in observing an appointment. Older English also used of: Milton writes "I see thou art exact of taste" in Paradise Lost (1667). Its closest companions are methodical and punctual, words for conduct rather than for things.

3. 3
   adjective

   Clearly and strictly defined, whether in thought or in words.

   Philosophers prize an exact statement of a problem over a vague one.

   The contract uses exact language so that no clause can be misread.

   Similarprecise, strict, explicit, specific, rigorous

   Oppositevague, imprecise, loose, ambiguous

4. 4
   verbtransitive or intransitive

   To demand and enforce the payment or performance of something, sometimes forcibly or imperiously.

   The warlord exacted tribute from every town along the river.

   Collectors exact payment whether the harvest was good or bad.

   Similarextract, extort, demand, levy, collect

   Note

   The verb keeps the other half of exigō, "demand, claim as due," the Latin word traced under the "precise" adjective. It names what is demanded and puts the person after from: to exact tribute, fees or obedience from someone. The King James Bible of 1611 has "Exact no more than that which is appointed you." The object need not be money; Clarence Thomas said Ruth Bader Ginsburg "exacted the best from each of us."

5. 5
   verbtransitive

   To make something desirable or necessary.

   Such a delicate operation exacts great skill from the surgeon.

   The new safety rules exact constant attention from the crew.

   Similardemand, require, necessitate

   Note

   Here the demand comes from circumstances rather than from a person: a task or a plan exacts what it needs. Philip Massinger, writing around 1621–1623, makes the person the object. "My designs exact me in another place" means my plans call me elsewhere. In current use the object is usually the thing required, often followed by from: an operation exacts skill from a surgeon. Beneath both lies Latin exigō, "demand, claim as due."

6. 6
   verbtransitive

   To inflict something or forcibly bring it about; to visit upon.

   The storm exacted a heavy toll on the coastal towns.

   Years of overwork exact a price from the body.

   Similarinflict, take, impose, wreak

   Note

   A darker turn of the demanding verb, where what is exacted is harm rather than payment. It takes on for the one who suffers, as in to exact revenge on someone, while the "demand payment" verb takes from. Toll and price are typical objects, usually in a figurative sense: a storm, or years of overwork, exacts a heavy toll.

7. 7
   adverb

   In a precise, conforming manner; exactly.

   She repeated the message exact, word for word.

   The craftsman fitted the joints exact, leaving no gap.

   Similarprecisely, accurately, perfectly

   Oppositeapproximately, roughly

   Note

   A flat adverb: the bare adjective form does an adverb's work and means the same as exactly. Its most familiar use is the intensifying the exact same, as in "She's wearing the exact same sweater as I am!", where exact strengthens same. It compares only with more and most (more exact, most exact) and has no -er form.

8. 8
   adjective

   Of a sequence, with the kernel of each map equal to the image of the preceding map.

   The students proved that the sequence was exact at every term.

   An exact sequence guarantees that the image of one map matches the kernel of the next.

   Note

   Homological algebra's central property, applied to a sequence of morphisms in an abelian category. A sequence can be exact at a single term, where one kernel meets one image, or exact throughout. In a short exact sequence, three objects sit between zeros, which forces the first map to be injective and the last surjective. Unlike the everyday adjective, it is not comparable: a sequence is exact or it is not.

9. 9
   adjective

   Of a functor, preserving short exact sequences.

   They checked whether the functor was exact before applying it.

   An exact functor sends short exact sequences to short exact sequences.

   Note

   The same word lifted from sequences to functors between abelian categories, defined through exactness of sequences. A functor qualifies when it carries short exact sequences to short exact sequences whole. One that keeps only part of that structure is called left exact or right exact instead. The bare adjective is reserved for functors that preserve everything.

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