1. a small cap or net worn to hold the hair in place or to protect a hairstyle
Usage: often used for sleeping or styling
2. any of various mosses of the family Polytrichaceae, having a distinctive cap-like structure
Usage: botany; also called hair moss

Examples

• She wore a haircap to bed to keep her curls neat.
• The haircap protected her hair while she showered.
• Haircaps are useful for maintaining elaborate hairstyles overnight.
• The haircap moss grows in moist, shaded areas of the forest.
• Botanists identified several species of haircap in the woodland sample.