Cuddle

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early 16th century (rare before the 18th century): of unknown origin.

wiktionary

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Origin uncertain, but probably from a frequentative form of Middle English *cudden, cuththen, keththen(“to embrace”), a variant of cuthen, kuthen, kithen(“to be familiar with, make known”), from Middle English cuth, couth(“known, familiar”), equivalent to couth +‎ -le. Cognate with Middle Dutch kudden(“to come together, flock together”). More at couth.

etymonline

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cuddle (v.)

"hug, embrace so as to keep warm; lie close or snug," 1520s (implied in cudlyng), of uncertain origin. OED calls it "A dialectal or nursery word." Perhaps a variant or frequentative form of obsolete cull, coll "to embrace" (see collar (n.)); or perhaps from Middle English *couthelen, from couth "known," hence "comfortable with." It has a spotty early history and seems to have been a nursery word at first. Related: Cuddled; cuddling. As a noun, "a hug, an embrace," by 1825.