Drooping or falling of the upper eyelid, which can be partial or complete. It may be congenital or acquired, caused by muscle weakness, nerve damage, or aging.
From Greek 'ptosis' meaning 'falling' or 'drooping.' The term was adopted into medical terminology in the 19th century to specifically describe eyelid drooping, though the root is used in other medical terms describing organ prolapse.
Ptosis can be a crucial diagnostic clue - when it's sudden and severe, especially with other symptoms, it might indicate a life-threatening brain aneurysm pressing on nerves! Interestingly, some people with mild ptosis unconsciously raise their eyebrows or tilt their head back to compensate, creating a characteristic facial expression that can be spotted from across the room.
Complete word intelligence in one call. Free tier — 50 lookups/day.