/ ˈmeɪnli; NAmE / adverb
1.
more than anything else; also used to talk about the most important reason for sth
SYN chiefly , primarily :
They eat mainly fruit and nuts.
'Where do you export to?' 'France, mainly.'
The population almost doubles in summer, mainly because of the jazz festival.
2.
used to talk about the largest part of a group of people or things :
The people in the hotel were mainly foreign tourists.