Under-keeper

noun
1.
a person who guards or watches, as at a prison or gate.
2.
a person who assumes responsibility for another’s behavior:
He refused to be his brother’s keeper.
3.
a person who owns or operates a business (usually used in combination):
a hotelkeeper.
4.
a person who is responsible for the maintenance of something (often used in combination):
a zookeeper; a groundskeeper.
5.
a person charged with responsibility for the preservation and conservation of something valuable, as a curator or game warden.
6.
a person who conforms to or abides by a requirement:
a keeper of his word.
7.
a fish that is of sufficient size to be caught and retained without violating the law.
8.
Football. a play in which the quarterback retains the ball and runs with it, usually after faking a hand-off or pass.
9.
something that serves to hold in place, retain, etc., as on a door lock.
10.
something that lasts well, as a fruit.
11.
guard ring.
12.
an iron or steel bar placed across the poles of a permanent horseshoe magnet for preserving the strength of the magnet during storage.
noun
1.
a person in charge of animals, esp in a zoo
2.
a person in charge of a museum, collection, or section of a museum
3.
a person in charge of other people, such as a warder in a jail
4.
See goalkeeper, wicketkeeper, gamekeeper
5.
a person who keeps something
6.
a device, such as a clip, for keeping something in place
7.
a soft iron or steel bar placed across the poles of a permanent magnet to close the magnetic circuit when it is not in use
noun

See trapper
keeper

noun

Someone or something worth keeping or trying to keep: This husband’s a keeper