Simple past tense and past participle of sun.(verb)
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Use "sunned" in a sentence
"Here in a bathhouse made of fresh-cut logs they changed into their bathing suits, swam, went boating in the warrior canoes he had brought back from the South Seas, sunned themselves on the dock, played leap frog and jousted, Indian-wrestled and boxed, dumped into the lake men who went boating in their street clothes."
"Turtles sunned on logs, and huge canebrakes filled the backwaters."
"A pair of mallards sunned themselves on plump moss."