Dearest is what you call someone you love, as if it were their name in that moment: Yes, dearest. Sleep well, dearest. Letters still open with Dearest Mum or My dearest friend. It is warm and close — partners, family, very old friends — and it can sound a little old-fashioned or like a line in a story, though people still say it when they mean it. It is the superlative of dear, “the most dear,” used as a way to speak to a person, not as a school grammar drill. Though actually, dearest can also mean “most expensive” (the dearest room in the hotel) or “most precious” in a quieter way. That is the same spelling, but this entry is the love-word you use when you speak to someone. It is intimate. Used with the wrong person it can sound as if you are a couple, or as if you are talking down from a stage play.