Definition
False friends are pairs of words from different languages that look or sound very similar but mean different things, or overlap in meaning only partly. They're a classic trap for language learners, who casually apply what they know from their native language and end up with strange misunderstandings and mistakes.
The Language Doppelgänger That Fools You with a Familiar Face
Have you ever been walking down the street, spotted someone who looked exactly like a close childhood friend, rushed over to say hi, and then realized they were a total stranger? False friends are exactly that in the world of language: strangers who only look like someone you know.
When we first start learning a foreign language, a familiar spelling or sound makes us happy, and it's easy to jump to the conclusion that the word means the same as the one in our native language. Take the Spanish word 'embarazada.' It's tempting to think of the English word 'embarrassed.' But it actually means 'pregnant.' So you set out to say, "I was so embarrassed yesterday," and end up announcing, "I got pregnant yesterday."
The German word 'Gift' is another classic. To an English speaker it looks like a lovely 'present,' but in German it means deadly poison, something that can harm or kill a person. Guess a meaning from a similar look, and you can land in an awkward situation that's the exact opposite of what you meant.
How Did Twin Words Become Strangers?
False friends come about in two main ways. The first is when words started out long ago in the same ancestor language, but as time passed each went its own way, so their meanings evolved differently.
English is a Germanic language, but it has borrowed a huge number of words from French and Latin. A word with the same root, passed from Greek through Latin, settled in French as 'sympathique,' meaning 'likable, pleasant.' In English, though, 'sympathetic' hardened into mostly meaning 'feeling pity, understanding someone's feelings.' The root was the same, but over the years the culture of each language community pulled the meanings apart.
The second way is when the words have no family tie at all and just happen to sound alike by chance. In Korean, 사이비 (saibi, 似而非, meaning something that only looks like the real thing) sounds a lot like the English word 'cyber,' but their origins and meanings have nothing to do with each other. Likewise, the English word 'numb,' meaning without feeling, and the Korean word 남 (nam, meaning 'another person') share a sound only by coincidence, while their real meanings are worlds apart. There are plenty of cases like that.
To Be More Precise: Totally Different vs. Oddly Overlapping
Linguists look at false friends more closely and split them into 'total false friends' and 'partial false friends.'
Total false friends are pairs like the German 'Gift' (poison) and the English 'gift' (present), where the meanings don't overlap at all and are opposite or completely unrelated. The Korean 대장부 (daejangbu, 大丈夫, meaning a brave, hearty man) and the Japanese 'daijobu' belong here too. They use the same Chinese characters, but the Korean word means a bold, big-hearted, heroic man, while the common meaning in modern Japanese is 'it's okay' or 'no problem,' so there's almost no overlap in everyday life. The shock of a mistake with these words is so big that, once you've learned them, it's relatively easy to stay careful.
The truly tricky ones are partial false friends, where the meanings overlap only in part. The Korean loanword 서비스 (seobiseu, meaning service) and the English 'service' are like that. Both can mean 'waiting on customers,' but in Korean, a freebie a shop throws in for nothing is also called 서비스, while English 'service' has no such meaning. In some contexts the word works as is, and in others it's off, so even advanced learners often fall into the trap by trusting the overlapping part and using the word anyway.
Common misconceptions
False friends only show up between Western languages that use the alphabet.
They're very common between Asian languages too, such as Korean, Japanese, and Chinese, which share Chinese characters or happen to sound alike.
Where you meet it
Mistaking the Spanish 'embarazada' (pregnant) for the English 'embarrassed.'
Mistaking the German 'Gift' (poison) for the English 'gift' and saying thank you for it.
The Korean 대장부 (daejangbu, a brave, hearty man) and the Japanese 'daijobu' (okay), which share the same characters but have drifted to different meanings.
In one sentence
They're words that look and sound alike but mean different things, or overlap only in part, which makes them easy for language learners to mix up.