) = conhecido (alguém que vc conhece mas não um amigo propriamente)
(1) a person that you know but who is not a close friend.
-Claire has a wide circle of friends and acquaintances.
-He's just a business acquaintance.
-I bumped into an old acquaintance on the train.
(2) [uncountable, countable] acquaintance (with somebody) (formal) slight friendship.
-He hoped their acquaintance would develop further.Acquainted
) = (1)familiarizado, conhecido...
-The students are already acquainted with the work of Shakespeare.
-Employees should be fully acquainted with emergency procedures.
(2) not close friends with somebody, but having met a few times before.
-We got acquainted at the conference (= met and started to get to know each other). (source Oxford Dictionary)