na-adjective
inefficient
Describes processes, systems, or methods that waste time, energy, or resources. Often used in business or technical contexts.
このやり方は非効率だ。
This method is inefficient.
非効率な会議を減らしたい。
I want to reduce inefficient meetings.
無駄 means 'wasteful' or 'useless', focusing on the result of inefficiency, while 非効率 describes the lack of efficiency itself.
Formed from 非 (negative prefix) + 効率 (efficiency).