I was reading a manga on Mangarock in English when I saw this idiom. Can you explain to me why the meaning of the idiom "jig is up" is "discovered in the act of dishonesty"?
'X is up' is an idiom meaning 'X is finished'
'the jig is up' is also an idiom
Definition of the jig is up
US, informal + old-fashioned
—used to say that a dishonest plan or activity has been discovered and will not be allowed to continue
The jig is up: where did you hide the stolen goods?
Jig is an old term for a lively dance, and in the Elizabethan era the word also became slang for a practical joke or a trick. This idiom derives from this obsolete slang word.
- late 16C SE, a comical performance, usu. given in the interval or at the conclusion of a play.
Jig is up/over:
(also jigg) a trick, a swindle; thus as verb, to trick; jigger noun, a swindler; thus the jig is up/over, the game is up:
1611 - J. Cook Greenes Tu Quoque Scene xvi: Why but what Jigge is this?
1777 - Maryland Journal 17 June n.p.: Mr. John Miller came in and said, ‘The jig is over with us.’.
According to Merriam-Webster's Dictionary https://www.merriam-webster.com/dictionary/jig:
1a: any of several lively springy dances in triple rhythm
1b: music to which a jig may be danced
2: TRICK, GAME —used chiefly in the phrase the jig is up
The definition follows the entry from Etymologyonline:
The name of the dance was the first meaning of the word. From 1580s JIG is used as the music for such a dance. The extended sense "piece of sport, trick" (1590s), survives mainly in the phrase the jig is up (first attested 1777 as the jig is over).
According to Merriam-Webster's Dictionary https://www.merriam-webster.com/dictionary/up:
at an end // your time is up
So, the original meaning of the idiom is 'the trick or the game has finished; everything's clear'.
As TRICK usually some negative connotation (according to MWD: ''a crafty procedure or practice meant to deceive or defraud'' https://www.merriam-webster.com/dictionary/trick), hence the modern meaning.
In my opinion, "jig" here is used with the meaning "bait". The meaning derives from the literal meaning "leaping up and down movements". As you can imagine, we do divert attention from the fish by jiggling the bait up and down. And if we see "jig" here as bait, then "jig is up" means "the bait is up". If we see bait as something that motivates one to do unacceptable things, like fish wanting to catch the bait so badly, when you pull the "bait" up by turning the reel, the perpetrator is also revealed to all. And like a fish, the perpetrator will be "eaten", by which i mean punished or condemned. So that's why i deduced, based on logic, that "jig is up" means "discovered in the act of dishonesty". And one more thing, the reason for the "dishonesty" part is because the fish is chasing the bait when it's discovered, referring to an unacceptable goal.