The place where the optic nerve attaches to the retina, and so where the retina cannot detect light.
A location where radio reception and/or transmission is significantly poorer than in surrounding locations.
A location around an earthquake epicentre that is prone to earthquake.
An inability to recognize a fact or think clearly about a certain topic, especially because of a prejudice.
The part of the railway/tramway track that cannot be seen in the side mirror or the side window.
In driving, the part of the road that cannot be seen in the rear-view mirror.
A subject or area about which one is uninformed or misinformed, often because of a prejudice or lack of appreciation.
In a stadium or auditorium, any location affording those seated or standing there only an obstructed visual or auditory experience.
The distinguishing features of a navigational light on a lighthouse etc by which it can be identified (colour, pattern of flashes etc.).
A distinguishing feature of a person or thing.
For a given field or ring, a natural number that is either the smallest positive number n such that n instances of the multiplicative identity (1) summed together yield the additive identity (0) or, if no such number exists, the number 0.
The integer part of a logarithm.
Being a distinguishing feature of a person or thing.