In this post I’d like to go over a useful Japanese word: うそ (uso), which means a lie, or more accurately something that is not true. The Kanji for uso is made up from a few different radicals, but the two biggest ones mean mouth (口) and tiger (虎):

嘘

This term is especially useful in casual conversation, as in the following dialogue:

• Person A: 新しいパソコンを買ったよ  (atarashii pasokon wo katta yo!)
• Person B: 嘘！ (uso!)
• Person A: I bought a new computer!
• Person B: You’re kidding!

It’s important not to think of uso‘s definition as simply “a lie”, since the connotation of a “lie” in English is a bit more sinister, often implying purpose and bad intentions. The “something that is not true”  (本当じゃない事) is a better way to define and remember it.

You can use this same expression in other forms like 「嘘だ」、「嘘だろう」、「嘘でしょう」, each with a different nuance. Just be careful, just because you use でしょう (which is technically polite language) doesn’t mean it is appropriate to say this phrase to a superior or senior.

You can also use this in reverse by saying: (for example, after you purposefully lied to someone)

• 嘘だよ！ (uso da yo!)
• Just kidding!   (Note: depending on the context saying the more literal “It’s a lie!” or “I’m lying” might be more appropriate as translations)

Here is another sample using 嘘:

• 何が本当か何が嘘か分からない  (nani ga hontou ka nani ga uso ka wakaranai)
• I don’t know what’s true and what isn’t.

If you want to say “lie” as a verb, typically you use the verb つく after 嘘.

• 嘘つくな！ (uso tsuku na)
• Don’t lie!

You may be reminded of the verb pair つく（付く）/  つける（付ける), but the verb つくused with 嘘 is not related to this, and  is actually transitive like 付ける. This つく is almost always written in hiragana, but technically you can write it in Kanji as 吐く. (To make matters more confusing that same Kanji can also be read as はく (haku), with the meaning of “spit up”, “throw up”, etc.)

What about “liar”, someone who lies? That’s easy, just use the noun/pre-masu form of つく, and you end up with “嘘つき” (usotsuki):

• あいつは嘘つきだよ (aitsu ha utsotsuki da yo)
• That guy/gal is a liar!

Other useful expressions are 嘘っぽい (usoppoi), which means something like “(that) seems like a lie”, and “嘘ばっかり” (uso bakkari) which means someone is “all lies” or “full of lies”.

That reminds me of the word 嘘っぱち (usoppachi) which is an emphatic version of 嘘. This is one of the few words that a Japanese person told me they were surprised to hear a non-native speaker use. I don’t remember where I picked it up, but I don’t generally see it in novels or dramas.

The name of the One Piece character Usoppu (ウソップ) also derives from the word “uso”.

The word 偽り (itsuwari) is basically a synonym for “uso”, however it has more a formal/literature nuance, so depending on the situation I might translate it as “falsehood”. I’ve seen in song lyrics as the phrase 偽りのない (itsuwari no nai) or 偽りがない (itsuwari ga nai) which literally means “no lie(s)”, but can be more properly translated as “sincere” or “truthful”.

If you are looking for how to describe misleading someone (possibly with lies), you can use the verb 騙す (damasu), which means “deceive” or “trick”.