Definify.com
Webster 1913 Edition
Prompter
Prompt′er
,Noun.
1.
One who, or that which, prompts; one who admonishes or incites to action.
2.
One who reminds another, as an actor or an orator, of the words to be spoken next; specifically, one employed for this purpose in a theater.
Webster 1828 Edition
Prompter
PROMPT'ER
,Noun.
1.
One that is placed behind the scenes in a play-house, whose business is to assist the speakers when at a loss, by uttering the first words of a sentence or words forgotten; or any person who aids a public speaker when at a loss, by suggesting the next words of his piece.