An expression or token of approval, endorsement, or appreciation; applause, praise. Obsolete.

figurative. A declaration of approval or support. Now chiefly in singular. Cf. sense 5a.

a sanction or endorsement, sometimes formally awarded but usually without this implication; an indication of satisfaction or acceptance.

figurative. A mark of approval or admiration; a bestowal of praise, a plaudit; an acknowledgement of distinction or merit, an award or privilege…

A pat on the back (either literal or figurative), given as a gesture or expression of approval or congratulation.

With the. Approval to go ahead with a course of action or to take on a function. Chiefly in to get the nod, to give the nod.

colloquial. nice one: expressing approval or congratulations for something done well. In later use also ironically.

In the context of social media: an expression of approval or support made by clicking on a particular icon.