reason

A cause or an explanation for something that has happened or that someone has done.

• The reason behind his decision is unknown.
  Kararının sebebi bilinmiyor.
• What's the reason for your visit?
  Ziyaretinizin nedeni nedir?

A fact or a situation that makes it right or fair to do or feel something.

• We have good reason to believe he's telling the truth.
  Doğruyu söylediğine inanmak için haklı gerekçelerimiz var.
• There is no reason to be afraid of the dog.
  Köpekten korkmak için haklı bir neden yok.

The ability of the mind to think, understand and form judgements in a logical way.

• Use your reason and don't just react.
  Aklını kullan, sadece tepki verme.
• Humans are different from animals because of their power of reason.
  İnsanlar akıl yetileri sayesinde hayvanlardan ayrılır.

What is sensible, practical or possible.

• I tried to make him see reason, but he wouldn't listen.
  Aklını başına almasını sağlamaya çalıştım ama beni dinlemedi.
• You can eat anything you like, within reason.
  Makul ölçüde istediğin her şeyi yiyebilirsin.