sweetest
adj.adj. the most pleasant or sugary of all. You use this to describe the thing with the most sugar or the person with the kindest personality.
adj. the superlative form of 'sweet'; describes the highest degree of sugary flavour or the most pleasant and kind disposition.
This is the sweetest apple I have ever tasted.
She is the sweetest person in the office and always brings treats for everyone's birthday.
The victory felt like the sweetest moment of his career, especially after the years of public criticism and physical injury he had endured to reach the podium.
Superlative form of 'sweet'; typically preceded by the definite article 'the'.
the most sweetestthe sweetestShort adjectives like 'sweet' form the superlative by adding '-est' — using 'most' as well is a double superlative error.