Superlative form of pretty: most pretty.(adjective)
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Use "prettiest" in a sentence
""Now, that's what I call the prettiest view we've seen of that gunboat yet, Mr Burnett, sir," said the carpenter a short time later, as the lad strolled up to where he was leaning over the bulwarks shading his eyes from the sun."
""That's what I calls the prettiest shot I ever see," said one of the men."
"Show him pictures of pretty girls, and the girl he calls prettiest will have dilated pupils."