Other forms: cuddling, cuddles, cuddled
To cuddle is to hold somebody close and warmly. Arms right round, and no hurry to let go.
It is affectionate rather than romantic, which is why children, grandparents and dogs are all cuddled, and it works as a noun, so asking for a cuddle is a small and perfectly ordinary request. The phrasal cuddle up describes settling close on a sofa. Cuddly describes anything soft enough to want to hold, and a cuddly toy is a whole category of present.
Cuddle probably comes from being familiar. Middle English cudden meant to embrace, a variant of kithen, to be familiar with, from couth, meaning known.
Middle English
*cudden
English, today
cuddle
Built from
Origin unknown, 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.
Etymology from Wiktionary, CC BY-SA