Night blindness is a condition where a person has difficulty seeing in low light or at night. There are several synonyms that can be used to describe this condition. One of the most common is nyctalopia. This term is derived from Greek and literally means "night blindness." Other synonyms include nocturnal amblyopia, which is a condition where the eyes are not able to adjust to low light, and hemeralopia, which is the opposite of nyctalopia and refers to a condition where the eyes are unable to adjust to bright light. Other terms that may be used to describe night blindness include impaired night vision, difficulty seeing at night, and poor night vision.