Exactly is an antonym of approximately.
Approximately is an antonym of exactly.
As adverbs the difference between approximately and exactly
is that
approximately is imprecise but close to in quantity or amount while
exactly is (manner) without approximation; precisely.
As a interjection exactly is
(
signifies agreement or recognition).
approximately English
Alternative forms
* (abbreviation)
Adverb
( )
Imprecise but close to in quantity or amount.
 In every box of matches there are approximately 40 matchsticks.
 Per 100g of chocolate there are approximately 11.6g of saturated fat.
 ...approximately 60 beats per minute.
Synonyms
* around, near, nearly, almost, about, loosely, roughly, close to
Antonyms
* accurately, definitely, exactly, precisely
Related terms
* approximate
See also
* circa

exactly English
Adverb
( en adverb)
(manner) without approximation; precisely.
 Measure exactly so we can be sure it is right.
 The edge is not exactly straight.
(focus) Used to provide emphasis.
 It was exactly an Eastern gray squirrel.
 He divided the coins exactly in half.
 He did it that way exactly to prove the point.
 His complaint was exactly that she failed to meet the deadline by four days.
Antonyms
* approximately
Interjection
( en interjection)
(Signifies agreement or recognition)
 So you're saying that we have only three days left? / Yes, exactly !
