A no-frills bra that is designed purely for functional, not decorative or fashion, reasons. Usually comes in basic, no-messing-about colors, like white, nude, and black.
Friend 1: Oooh...those are some sexyunderwear! Hot date tonight?
Friend 2: No, unfortunately. It's laundry day today, so all my utititarian bras are in the wash!
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.