Real Dictionary

night light
countable noun: A night light is a light that is not bright and is kept on during the night, especially in a child's room.

night light in American English
a small, dim light kept burning all night, as in a hallway, bathroom, or sickroom

night-light in American English
noun: a usually dim light kept burning at night, as in a child's bedroom

night-light in British English
noun: a dim light burning at night, esp for children