noun
working day; workday
Refers to a day on which work is performed, as opposed to a holiday or day off. Often used in labor or scheduling contexts.
今日は労働日なので、朝から晩まで働きます。
Today is a working day, so I'll work from morning till night.
労働日と休日をはっきり分けたい。
I want to clearly separate working days and days off.
平日 means 'weekday', a day that is not a weekend or public holiday, but not necessarily a working day for everyone.
Compound of 労働 (ろうどう, 'labor') and 日 (び, 'day').