No dillydallying today: we are getting directly to the question of how dillydally made its way into our lexicon. We’ve said it before and we’ll say it again: dillydally is a reduplication of dally. Reduplication is the term for "an often grammatically functional repetition of a radical element or a part of it occurring usually at the beginning of a word and often accompanied by a change of the radical vowel." (来源：EnglishCN.com)

To dally is to "act playfully" or " deal lightly." To dally is also to " waste time; linger; or dawdle." This latter sense is the one that gave us dillydally, meaning "to waste time by loitering or delaying; to dawdle."

To dawdle is to spend time lackadaisically, that is, with a carefree indifference marked by halfhearted efforts. We won’t waste any time on the stories behind dawdle and dally (unknown, and none too interesting, respectively: dally comes from the Anglo-French dalier), but lackadaisical does have a doozy of a history. It comes from lackaday, a now-archaic term used to express regret or deprecation that was itself a shortening and alteration of the synonymous (and also-archaic) alack the day.