One who keeps something.
"The zoo keeper ensures that all the animals are fed and cared for properly."
An English surname, from occupations for the keeper of a castle.
"The Keeper family has lived in the village since the medieval era when their ancestor was appointed to guard the local fortress."
The word keeper comes from Middle English and originally meant a person who keeps or guards something. It entered modern usage through the straightforward combination of the verb "keep" with the agent suffix "-er.