Translation guide
The English verb "buy" has several common Japanese equivalents, but the most general and useful is 買う (kau). However, Japanese often uses different verbs depending on what is being purchased, the formality of the situation, and whether the focus is on the transaction or the act of obtaining something.
To obtain something by paying money; the most common, everyday meaning of "buy".
The default verb for buying goods, tickets, etc. Used in casual and polite contexts.
昨日、新しい本を買った。
I bought a new book yesterday.
I'll buy a rice ball at the convenience store.
A more formal term, often used in business or official contexts, or for larger purchases like a house or car.
I purchased a new car.
To pay for someone else's meal or drink, often as a friendly gesture.
Means to treat someone to a meal or drink. The person being treated is marked with に.
It's my treat today.
My senior treated me to lunch.
To accept something as true, often used in negative or skeptical contexts.
To delay something in order to gain more time.
Literally 'to earn time', the most natural way to express 'buying time'.
He tried to buy time by asking questions.
To pay someone illegally or unethically to get something done.
While English can 'buy' ideas, time, or loyalty, Japanese 買う is mostly limited to physical goods or tickets. For metaphorical uses, choose the specific phrases above.
買う is everyday and covers most situations. 購入する is formal and often used in writing or for significant purchases. In casual speech, 買う is always safe.
その話、信じられない。
I can't buy that story.