A blind spot is the area you cannot see however hard you look. Check your blind spot, a blind spot in the mirror, a real blind spot about it.
The eye has a literal one where the optic nerve leaves the retina, and the brain fills it in so convincingly that nobody notices. In driving it is the area no mirror covers, and figuratively it is a subject somebody cannot judge fairly.
1nounblind spotThe area you cannot see however hard you look.
“A cyclist was in my blind spot, so I didn't see him when I changed lanes.”
blind spot is an area.
Blind plus spot, first used of the point in the eye where the optic nerve leaves the retina.
From blind + spot.
Etymology from Wiktionary, CC BY-SA
Practised in Ways of Looking