rein vs keep

rein and keep both are nouns.

Word	Noun	Adjective	Verb	Adverb
rein	Yes	No	Yes	No
keep	Yes	No	Yes	No

As verbs, keep is a hypernym of rein; that is, keep is a word with a broader meaning than rein:

Other hypernyms of rein include hold back, keep back, restrain.

rein (noun)	keep (noun)
one of a pair of long straps (usually connected to the bit or the headpiece) used to control a horse	the main tower within the walls of a medieval castle or fortress
any means of control	a cell in a jail or prison
	the financial means whereby one lives

rein (verb)	keep (verb)
keep in check	prevent (food) from rotting
stop or slow up one's horse or oneself by or as if by pulling the reins	prevent the action or expression of
stop or check by or as if by a pull at the reins	stick to correctly or closely
control and direct with or as if by reins	maintain by writing regular records
	supply with necessities and support
	hold and prevent from leaving
	retain possession of
	look after; be the keeper of; have charge of
	retain rights to
	maintain for use and service
	have as a supply
	store or keep customarily
	stop (someone or something) from doing something or being in a certain state
	allow to remain in a place or position or maintain a property or feature
	conform one's action or practice to
	behave as expected during of holidays or rites
	cause to continue in a certain state, position, or activity
	supply with room and board
	maintain in safety from injury, harm, or danger
	fail to spoil or rot
	continue a certain state, condition, or activity
	to rear