I excerpt various websites.
https://www.grammarphobia.com/blog/2013/01/hypercritical-hypocritical.html
Q: I was reading a posting on the religious blog Patheos about critics who are both “hypercritical” and “hypocritical,” which got me to thinking about those two words. They look like antonyms, but being “hypercritical” isn’t the opposite of being “hypocritical.” Are these terms related?
A: You’re right. The two adjectives aren’t antonyms. Someone who’s “hypercritical” is excessively critical while someone who’s “hypocritical” is insincere. But as that posting suggests, a “hypercritical” person can be “hypocritical.”
Are the words “hypercritical” and “hypocritical” related? Yes, if you go back far enough.
The English prefixes “hyper” and “hypo” are derived from the Greek prepositions hyper (over) and hypo (under). The “critical” part of these words ultimately comes from the classical Greek verb krinein (to judge, decide, etc.).
So someone who’s “hypercritical” is overly judgmental. But why, you’re probably wondering, is a “hypocritical” person insincere?
In ancient Greek, according to the Chambers Dictionary of Etymology, hypokrinesthai meant to play a part, hypokrisis was acting on the stage, and hypokrites was an actor.
How did the classical terms hypo (under) and krinein (to judge) give the Greeks the terms for act, acting, and actor?
The etymology is fuzzy here, but one possibility is that the Greeks recognized that actors had to subordinate their own judgment to play a role.
Now how did hypokrisis, the Greek term for acting, give English “hypocrisy,” a negative word for professing beliefs you don’t really have?
It turns out that in classical times hypokrisis also had an unpleasant odor to it, according to Chambers. In addition to meaning acting, the term referred to pretense and dissimulation—that is, insincerity.
https://www.merriam-webster.com/words-at-play/hypocrite-meaning-origin
[...]
The word hypocrite ultimately came into English from the Greek word hypokrites, which means “an actor” or “a stage player.” The Greek word itself is a compound noun: it’s made up of two Greek words that literally translate as “an interpreter from underneath.” That bizarre compound makes more sense when you know that the actors in ancient Greek theater wore large masks to mark which character they were playing, and so they interpreted the story from underneath their masks.
The Greek word took on an extended meaning to refer to any person who was wearing a figurative mask and pretending to be someone or something they were not. This sense was taken into medieval French and then into English, where it showed up with its earlier spelling, ypocrite, in 13th-century religious texts to refer to someone who pretends to be morally good or pious in order to deceive others. (Hypocrite gained its initial h- by the 16th century.)
It took a surprisingly long time for hypocrite to gain its more general meaning that we use today: “a person who acts in contradiction to his or her stated beliefs or feelings.” Our first citations for this use are from the early 1700s, nearly 500 years after hypocrite first stepped onto English’s stage.
https://en.wikipedia.org/wiki/Hypocrisy#Etymology
The word hypocrisy comes from the Greek ὑπόκρισις (hypokrisis), which means "jealous", "play-acting", "acting out", "coward" or "dissembling".[4] The word hypocrite is from the Greek word ὑποκριτής (hypokritēs), the agentive noun associated with ὑποκρίνομαι (hypokrinomai κρίση, "judgment" »κριτική (kritikē), "critics") presumably because the performance of a dramatic text by an actor was to involve a degree of interpretation, or assessment.
Alternatively, the word is an amalgam of the Greek prefix hypo-, meaning "under", and the verb krinein, meaning "to sift or decide". Thus the original meaning implied a deficiency in the ability to sift or decide. This deficiency, as it pertains to one's own beliefs and feelings, informs the word's contemporary meaning.[5]
Whereas hypokrisis applied to any sort of public performance (including the art of rhetoric), hypokrites was a technical term for a stage actor and was not considered an appropriate role for a public figure. In Athens during the 4th century BC, for example, the great orator Demosthenes ridiculed his rival Aeschines, who had been a successful actor before taking up politics, as a hypocrites whose skill at impersonating characters on stage made him an untrustworthy politician. This negative view of the hypokrites, perhaps combined with the Roman disdain for actors, later shaded into the originally neutral hypokrisis. It is this later sense of hypokrisis as "play-acting", i.e., the assumption of a counterfeit persona, that gives the modern word hypocrisy its negative connotation.
