1. Plural of fossa; small pits, grooves, or depressions in a surface, especially in bone or anatomical structures.
Usage: anatomy; technical
2. Plural of fossa; a ditch or moat, especially one surrounding a fortification.
Usage: historical; architecture

Examples

• The cranial fossae are depressions in the skull that hold the brain.
• Medieval castles were often protected by deep fossae filled with water.
• The anatomist pointed out the various fossae on the bone specimen.
• Roman fortifications included fossae to defend against invaders.
• The temporal fossae on the skull provide space for the jaw muscles.