/ ˈduːdl; NAmE / verb
[ v ] to draw lines, shapes, etc., especially when you are bored or thinking about sth else :
I often doodle when I'm on the phone.
► doo·dle noun
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WORD ORIGIN
early 17th cent. (originally as a noun denoting a fool, later as a verb in the sense make a fool of, cheat ): from Low German dudeltopf , dudeldopp simpleton. Current senses date from the 1930s.