from dictionary.com’s definition of nerd

Others maintain that Dr. Seuss is the true originator of nerd and that the word nerd (a comically unpleasant creature) was picked up by the five- and six-year-olds of 1950 and passed on to their older siblings, who by 1957, as teenagers, had restricted and specified the meaning to the most comically obnoxious creature of their own class, a square.