Dearest has 3 different meanings across 1 category:
Noun
a beloved person; used as terms of endearment
"Dearest, please don't worry about me while you are away on your trip."
A beloved person; a term of endearment.
"I promised my dearest that I would be home before dinner."
superlative form of dear: most dear
"She held her dearest friend close during their final farewell, knowing no other bond could compare to theirs."