1 a : one who expresses a reasoned opinion on any matter especially involving a judgment of its value, truth, righteousness, beauty, or technique b : one who engages often professionally in the analysis, evaluation, or appreciation of works of art or artistic performances 2 : one given to harsh or captious judgment
While critics can be unbearable, the word critic originally referred (and still does refer) to someone who assesses a thing's quality or value—and where would we be without someone assessing quality and value for us? Watching worse movies and buying worse cars, probably.
Critic was borrowed from the Latin word criticus in the late 16th century but traces back to the Greek adjective kritikós, meaning "discerning, capable of judging." It predates the word referring to what a critic produces—criticism—by a few decades.