verb
happen
HAP-uhn/ˈhæpən/
To take place or come about.
The break happens as the bird lands on the fragile branch.

Etymology
Hap, “to come to pass,” linked an occurrence with good or bad fortune. Happen retains the idea of an event taking place without necessarily suggesting luck.
In context
Mutations can occur randomly. It can happen when DNA divides and the cell’s machines make mistakes.
More examples
- What happened yesterday?
- I happened to see her downtown.
- Nothing unusual has happened.
Forms
happen · happens · happened · happening
Similar words
- occur
- A more formal alternative for taking place.