long time

You usually place it after a verb. You can say you have been waiting for a long time. You can also use it as an adjective. A long-time friend is someone you have known forever. It is a very flexible tool for your English kit.

Use it when you feel the weight of the clock. Use it at a restaurant when the pizza is late. Use it when you see an old friend after many years. It works perfectly in texts like It's been a long time! It feels natural in almost every conversation.

Don't use it for specific measurements. If you mean exactly five minutes, say five minutes. Long time is about the feeling of time, not the math. Also, avoid it in very technical scientific reports. Scientists prefer precise numbers over feelings. Don't use it if the time was actually short but you are just being dramatic—unless you are joking!

English speakers are often obsessed with being on time. Because of this, long time often carries a bit of emotion. It can show patience or frustration. There is also the famous greeting Long time no see. This actually comes from a literal translation of Chinese grammar. It became a permanent part of English culture.

You will often hear a long time ago for the past. People also say for a long time to show something is continuing. If you want to be more casual, you might say a while. If you want to be dramatic, try forever. But long time is the classic choice that never fails.