私服

1. Origins, structure, and basic meaning

• Structure: 私服 is read しふく and means one's own clothes rather than a prescribed uniform.
• Basic usage: In この学校では金曜日だけ私服で登校できる。, students at this school may attend in their own clothes only on Fridays.

2. Common pitfalls and similar expressions

• The contrast with a uniform
  • 私服 contrasts with 制服. The key point is that the clothes are not the prescribed uniform, rather than how comfortable or informal they are.