1. relating to or situated at a lumen (the hollow space within a tubular structure)
Usage: medical; biological
2. relating to or characterized by being at a threshold or transitional state
Usage: formal; academic

Examples

• The luminal surface of the intestine is lined with specialized cells.
• Doctors examined the luminal diameter of the blood vessel.
• The catheter was placed in the luminal space of the artery.
• Researchers studied the luminal contents of the digestive tract.
• The patient experienced a luminal state between sleep and wakefulness.
• This luminal phase represents a critical transition period.