main reason — most important reason
collocationB1IELTS 5+neutralcommon
The biggest or most important reason for something happening or for a decision.
Say it like a native
Textbook The principal motivation behind my decision was financial.
Native The main reason was money.
'Main reason' is the plain everyday phrase; 'principal motivation' is essay-formal.
Pattern: the main reason (for something) is/was...
In use
- The main reason I moved to this city was for a better job.daily life
- The main reason I prefer public transport is because it’s more convenient and better for the environment.IELTS speaking
Common mistake
✗ The main reason of leaving was the pay.
✓ The main reason for leaving was the pay.
'Main reason FOR' something — not 'of'.
Common collocations
the main reason + for/why— for, why, behind, is that
Don't confuse it
‘Main reason’ is stronger and clearer than just ‘a reason’ or ‘an important reason’.