primary reason
noun phraseUK /ˈpraɪ.mə.ri ˈriː.zən/
US /ˈpraɪ.mer.i ˈriː.zən/
The main reason is the biggest or most important reason why something happens.
The primary reason I like summer is that I can swim every day.
RELATED WORDS
OTHER MEANINGS
2. The first or earliest reason in a list or order.
The primary reason listed on the form was a scheduling conflict.
3. The most basic or fundamental cause behind an event.
Scientists found that the primary reason for the flood was heavy rain.
4. The reason given first and most strongly when explaining a choice.
Her primary reason for choosing the blue bike was its color.