noun
busyness; being busy
Describes a state of being busy or having many things to do. Often used in formal or written contexts.
年末は繁用のため、返信が遅れました。
Due to busyness at the end of the year, my reply was delayed.
noun, noun or participle which takes 'suru', transitive verb
Refers to using something often or heavily. Can be used as a noun or with する to mean 'to use frequently'.
このアプリは繁用している。
I use this app frequently.
繁用によりバッテリーの消耗が早い。
The battery drains quickly due to heavy use.