reminder vs admonisher

reminder and admonisher both are nouns.

Word	Noun	Adjective	Verb	Adverb
reminder	Yes	No	No	No
admonisher	Yes	No	No	No

As nouns, reminder and admonisher are synonyms defined as:

reminder and admonisher: someone who gives a warning so that a mistake can be avoided

Other synonyms of reminder include monitor.

reminder (noun)	admonisher (noun)
an experience that causes you to remember something	someone who gives a warning so that a mistake can be avoided
a message that helps you remember something
someone who gives a warning so that a mistake can be avoided