Betrayal (noun)

1. The act of betraying someone or something, such as a friend, country, or principle.
2. An instance of being betrayed.

Origin:

From the old english word "þæræfian" meaning "to deceive".

Examples:

1. His betrayal of our trust was a huge blow to the team.
2. The betrayal of her husband's infidelity was devastating.
3. The country's leaders were accused of betrayal of the national interest.
4. The betrayal of his promise was a major disappointment.
5. The betrayal of the company's secrets was a serious crime.