or

Used to connect two or more possibilities or choices.

• You can call me or send an email.
  Beni arayabilir ya da e-posta gönderebilirsiniz.
• Would you like tea or coffee?
  Çay mı kahve mi istersiniz?

Used to say what will happen if someone does not do something.

• Hurry up, or we'll miss the bus.
  Acele et, yoksa otobüsü kaçıracağız.
• Wear a coat, or you'll catch a cold.
  Mont giy, yoksa üşütürsün.

Used in negative sentences to join two or more things that are all not true.

• She doesn't eat meat or fish.
  Ne et ne de balık yer.
• I didn't see or hear anything strange.
  Tuhaf hiçbir şey ne gördüm ne de duydum.

Used to introduce another name for something, or to correct what you have just said.

• We studied botany, or the science of plants.
  Botaniği, yani bitki bilimini çalıştık.
• I'll see you on Monday, or rather Tuesday.
  Pazartesi, daha doğrusu salı görüşürüz.

Used between two numbers, or in 'or so', to show that an amount is not exact.

• I'll be back in a day or two.
  Bir iki güne dönerim.
• There were twenty or so people at the party.
  Partide yirmi kadar kişi vardı.