Summary
In Dr. Seuss's 1950 composition of whimsy, If I Ran the Zoo, we have what seems to be the first occurrence of nerd in print. It's not until the 1960s, however, that nerd (as well as its alternate spelling nurd) takes off and starts appearing more frequently in running text.
Dr. Seuss's Nerd appears as more of a disapproving grouch than a "drip" or "square" Theories on the origin of nerd also include wordplays.
No hard evidence has surfaced in support of knurd as the source. Another theory related to the spelling nurd is that it is a euphemism of turd, which can refer to a contemptible person.
