As far as "lying" goes, what words mean is...

[Purple Knight]

Question for debate: When determining whether or not a lie was told, what is the proper frame of reference for determining what the words (and the statement) actually meant, and thus, whether or not it was a lie?

This option alone has the potential to be objective.

The Dictionary
One would think the dictionary is the best and fairest option. However, the dictionary itself says that it does not get to determine what words mean. The dictionary will tell you, its job is to absorb and catalog meaning from real usage.
https://www.dictionary.com/e/getting-wo ... tionaries/
The answer involves one of the most misunderstood things about dictionaries, so let’s set the record straight: a word doesn’t become a “real word” when it’s added to the dictionary. It’s actually the other way around: we add words to the dictionary because they’re real—because they’re really used by real people in the real world.

You can still vote for the dictionary, because nothing else is likely to be as impartial. You're simply voting that the dictionary mistakes its true role of determining orthodoxy of language and mistakenly gives itself the lesser role of mere curation. There are dangers of both. If the dictionary believes itself to be dictator, real usage may fail to be catalogued, and this may be out of bias. If the dictionary only curates, it is powerless to correct biased or unscientific usage, as long as that usage is the true convention among users of the language. (This is something the dictionary does claim to do, despite claiming to have no authority whatsoever, so it does find itself inconsistent on the point of whether it has authority or not.) This is the only option for someone who believes that deliberate deception does not equal a lie, because the dictionary may save the deceiver and render his statement technically true.

The following two options concern usage.

What the Speaker Means
I've in the past affirmed the right of people to use words as they wish. It's probably a good idea to try to avoid being confusing but I don't think it's necessary. If you're using a definition of "box" that works in just this example, as long as you've explained it, and it's useful, I will stand up for your right to do that, and I will try to stand up to anyone who tells you that you can't do that, because they think they own the word "box" and it can't mean what you're using it for. So you're not lying when you're talking about what a box is.

This also affirms your right to simply pick a definition from the dictionary, if there are many, and not have people jump down your throat for using definition #2 rather than definition #1. So arguably this option is needed, even if we affirm the authority of the dictionary over the formal phase of the language.

However, if the speaker meant to deceive, then what they meant by the words they used, was false, and is therefore a lie. Here's an example:

Assume Bob wants to deceive Mary. He says, "I'll go to the store after I shower." He then proceeds to shower but does not go to the store at all. When Mary questions this, he says that he will, at some point after he showers, surely end up at the store. The word after is the crux of this. If he did not mean to deceive, then he didn't lie either. But if he did mean to deceive, then he used the word after to mean "right after" at which point the statement becomes a lie, if words truly mean what the speaker intends. That's how he deceived: He meant right after.

What the Speaker Reasonably Believes the Listener Thinks they Mean
This is the most complicated option. And probably the least objective. This arguably gives the speaker an even greater duty not to deceive the listener, or else be caught lying.

But consider this scenario: Someone offers a child a false dictionary which they wrote. The child is able to look up meanings of words, but some of these are not the true meanings. Now, if you believe that the real dictionary alone determines meaning, and the adult has offered the child a false one, the adult who masterminded this state of affairs is now free to tell technical truths that the child has no way to perceive any way but wrongly. The child has no opportunity to correct its misconception.

And if this doesn't count as lying, then we can't ever say anyone has lied to us, because we always could have been slipped a false dictionary, which would render all lies mere deceptions, making the distinction useless. It is only if words mean what the speaker reasonably believes the listener will think they mean, that a lie can ever be labeled a lie at all.

Now, we don't need this option and can simply select dictionary, by simply adding the caveat that the dictionary we're using must be shared between the speaker and listener. But then it comes back to shared expectations about meanings, and we still need a way to allow the speaker to pick a meaning from the dictionary, if there are many.

One thing I can say for this option is that I believe it is the easiest and simplest to use when all participants are honest and of like mind on stipulative definitions, since I can simply tell you the stipulative definition of "box" I'm using, and then very well expect you to understand it. If, however, I know you're stubborn and will continue to understand something else, well then, I'm out of luck, I'm technically lying (which doesn't feel right when I've explained what I meant) and I ought not to have voted for this option.