There is a proverb saying "Once bitten, twice shy", and I am not sure what "twice" means here.
Does it mean
Once you are bitten, you get twice as shy as before
or
Once you are bitten, you get shy the next time
Also, does "once" means the same as the one in this sentence?
Is "once" in "Once bitten, twice shy" a conjunction or an adverb?
The literal meaning of the proverb is that after being bitten on one occasion a person will be shy on two occasions. The Free Dictionary gives multiple meanings, including "Once one is hurt by someone or something, one will be extra cautious to avoid that person or thing." "Twice shy" suggests that the extra caution continues to be exercised.
The grammar of the proverb is ambiguous due to its brevity. "Once" can be understood to mean "on a single occasion", but it could also be understood to mean "After being". This second understanding would be emphasised in a paraphrase "Once bitten you will be twice shy". I believe the first meaning is more likely because of the parallel structure where "once bitten" is matched with "twice shy".
Other interpretations of the proverb suggest that "twice" refers to being doubly cautious in the future. This would be clearer in the paraphrase "Once bitten, twice as shy". To me the word "shy" already indicates caution, and possibly excessive caution, so this interpretation is also less likely.
In this context, "twice" means, "the second time you think about doing that same thing". It's a misuse of the word "twice" which normally means "two times", and not "the next/second time".
Merriam-Webster defines the phrase:
—used to mean that a person who has failed or been hurt when trying to do something is careful or fearful about doing it again
In their definition, "twice" is represented by "doing it again"
There are two different questions you could ask. One is what the saying means, the other is what the words would mean if they were not a saying. The saying means that a person who has been hurt in the past will be cautious in the future. It does not mean any particular number of times or amount of caution.
The words, were they not a saying, would contrast the singularity of "once" with the duality of "twice". "Once X, twice Y" would say that one must only X a single time to Y more than once. That is, it would mean that a person who had been bitten a single time would be shy on two future occasions.
However, it's important to note that in the saying, it does not mean any particular number of times. It can just mean on a single future occasion. It can mean more than once. It just means a person hurt in the past is cautious in the future.
The first part of the phrase once bitten could be expanded as once you have been bitten. It is not referring exclusively to actually being bitten of course but to any unpleasant experience.
The second part twice shy could be expanded as the next time you will be more cautious. It does not refer, except loosely, to the second time. The assumption is that your caution will continue.
We also have a similar saying the burnt child fears the fire (or dreads the fire).
Merriam-Webster has a definition for this saying:
a person who has failed or been hurt when trying to do something is careful or fearful about doing it again
This is one of many proverbs that doesn’t make literal sense. If there’s any explanation for the way it uses “twice,” it has to do with regional slang in England centuries ago.
Another variation is,
Once bitten, the second time shy.
This has the same meaning. It’s more standard English, but much less common.
Yes twice shy leans towards the meaning of being more shy and knowing not to do it again, not explicity "twice".
And yes "once" here does usually mean someone does it one time, learns his lesson, doesn't do it again.
We use once to mean 'at a time in the past but not now', which fits your context, so it is an adverb.
once you are bitten by something, you will be twice as shy of it
The many meanings of "shy" all connect to avoidance or distancing. One of the meanings of the expression "shy of" is "afraid of" or "staying away from".
There is an embedded pun in the saying, contrasting the multiple senses of "once" and "twice".
"Shy" in this proverb is a verb meaning "to flinch" or "to react negatively to". We still use the word with horses (and sometimes other animals), to describe their response when they encounter scary situations and panic. It is not the adjective "shy" meaning "being cautious/fearful".
The meaning of the proverb is that if you are bitten once, you will naturally flinch away from the bite the first time - but the next time you're in a situation where you might be bitten, you'll flinch away before you're bitten. In other words, if you're in a situation where something bad happens to you, in future you'll react as if that bad thing was going to happen again.
In answer to your question about parts of grammar, both "once" and "twice" are adverbs counting a number of events, which can be called numeral adverbs, iterative numerals, or multiplicative numerals, depending on your grammar reference. "Once" is the count of the number of times you are bitten, and "twice" is the count of the number of times you shy.
Note that this reaction may be a good thing (learning from experience to avoid common hazards) or it may be a negative thing (reacting negatively when there isn't a real need to). The proverb can actually be used for both these meanings, which is interesting. Most proverbs have a "moral" meaning of what's good and bad, but this is more describing a situation and not exactly saying that the outcome is good or bad, only that it is what it is.
My insight tells me that the saying has its "punch" in contrasting what the biting party might expect: "that once bitten => once shy". But the point is to correct his expectation kind of saying "no Siree ... I am not taking it lightly, I am taking it twice as seriously as you would expect. It's not a one-to-one relationship". (If it was one-to-one the biter could set into motion a circularly-recurring-cyclical-cycle c=2rPI :)
