dapple: [14] Dapple is a puzzling word. It is presumably derived from or linked in some way to its contemporary dapple-grey (although this has never been proved), which has formal and semantic links with several colour terms in other Germanic languages (such as Old Norse apalgrár, German apfelgrau, and Dutch appelgrauw) that are surely too strong to be coincidental.
They all mean literally ‘a(chǎn)pplegrey’. Add to this such forms as French grispommelé, again literally ‘a(chǎn)pplegrey’, and Russian yablokakh ‘dappled’, a derivative of yábloko ‘a(chǎn)pple’, and the inference becomes even more compelling – that dappled is related in some way as yet unexplained to apple. Many of the above terms were applied specifically to grey horses marked with round blotches, and so perhaps the word had its beginnings in a perceived resemblance in shape between such markings and apples.
dapple (v.)
early 15c. (implied in past participle adjective dappled), perhaps from a Scandinavian source akin to Old Norse depill "spot," Norwegian dape "puddle." Perhaps a back-formation from, or merger with, Middle English adjective dapple-gray "apple-gray" (late 14c.), based on resemblance to the markings on an apple (compare Old Norse apalgrar "dapple-gray"), or, as it was used of gray horses with round blotches, perhaps via resemblance to apples themselves.