Invalid | Vocabulary | Khan Academy

Hello wordsmiths! The word we're featuring in this video is invalid. That's right, it's not true—or rather, that's what it means: incorrect, false, not accepted. It's an adjective.

It comes from Latin, where the prefix "in" means not and the word "valirus" means strong. So it literally means not strong or weak. A weak argument, a weak law—someone's argument might be invalid because it was based on faulty evidence.

When you look at invalid, can you recognize any other English words? Anything with "in" or "val" in it? Take 10 seconds of this music break to come up with some possibilities. Here we go!

[Music]

Validate—right? To prove that something's right or true. I validate your parking. I validate your feelings. Get you with the big validation stamp.

Value—meaning something that has worth, right? Strength and worth. And inability—which is when you cannot do something. There's ability, right? When it can do a thing, and inability—which is its opposite.

Let's spend some time talking about that "in" prefix, honestly, because it can get confusing. There are two different prefixes in English, both coming from Latin, that are spelled and pronounced the same way: "in" (i-n) that have different meanings.

"In" or sometimes "im" (I-m) means not—exactly like the native English "un," like unlikable, unlovely. Think invalid, impolite, infrequent—right? Not correct, not polite, not frequent.

And then there's "in" that means inside. This also sometimes appears as "e-n" (e-n), like "insight," looking inward, or "insert," which is to put something into something else. Or with "en," you can have it as enlist or enrich.

But today, in this video, we're talking about the "in" that means not. We will return to this topic for sure in other videos.

Now let's use invalid in a sentence: "I can't log in; it says my password is invalid." Makes you furious when something's invalid. It doesn't work; it isn't correct. When it's valid, it's proper and appropriate, but when it's invalid, it won't be accepted. It's no good.

You know what is good, though? You! You're good! I believe in you and the vocabulary journey that we're on together. You can learn anything.

David out.