Definition of class act in English English dictionary
An entity exhibiting high class (q.v.) esp. through refinement of demeanor, conscientiousness of behavior, and/or skillfulness in performance; or an exhibition of high class esp. of one or more of those types:
A display of the above characteristics, e.g., an event or an individual or collective action.
Used sarcastically, a person, entity, event, or action entity exhibiting the opposite of the above characteristics, i.e., boorish, unprincipled, and/or bungling behaviorDid you hear about Peter's "milk-milk-lemonade" toast to Lois at their wedding reception? After a class act like that, I'm surprised that anyone in the Pewterschmidt family is still speaking to him
One of distinctive and superior quality: "Academy members... tend to favor films that will make Hollywood seem a class act instead of a hotbed of money-grubbing vulgarians" (Jay Carr)