Monday, to many

• When some cycles occur
• Time to do the laundry
• Monday, to housewives
• A day set aside for doing household laundry
• Laundry time
• When to do laundry
• Toilsome part of the week

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ Why do they build such small sculleries which make washday a dread.

Wiktionary Word definitions in Wiktionary
n. A day when laundry is washed.