undertaking
US /ˈʌn.dɚˌteɪ.kɪŋ/
UK /ˈʌn.dɚˌteɪ.kɪŋ/

1.
a formal pledge or promise to do something
:
•
He gave a solemn undertaking to complete the project on time.
•
The company gave an undertaking not to disclose confidential information.
2.
a task or enterprise, especially a large or difficult one
:
•
Building the bridge was a massive undertaking.
•
Starting a new business is a challenging undertaking.