noun, noun which may take the genitive case particle 'no'
mainstream; main current; prevailing trend
Refers to the dominant trend, opinion, or approach in a field, society, or culture. Often used with の to modify nouns.
彼の意見は党の主流とは違う。
His opinion differs from the party mainstream.
このデザインは今年の主流になりそうだ。
This design looks set to become this year's mainstream trend.
noun
main stream; main course (of a river)
Geographical use for the primary channel of a river, as opposed to tributaries or branches.
この川の主流は山の北側を流れている。
The main stream of this river flows along the north side of the mountain.