nobody (n.)

"not in any degree, not at all," Middle English, from Old English na, from ne "not, no" + a "ever." The first element is from Proto-Germanic *ne (source also of Old Norse, Old Frisian, Old High German ne, Gothic ni "not"), from PIE root *ne- "not." Second element is from Proto-Germanic *aiwi-, extended form of PIE root *aiw- "vital force, life, long life, eternity." Ultimately identical to nay, and the differences of use are accidental.

As an adjective, "not any, not one, none" (c. 1200) it is reduced from Old English nan (see none), the final -n omitted first before consonants and then altogether. As an interjection making a negative reply to a statement or question, "not so," early 13c., from the adverb. As a noun, 1580s as "a denial; a negative vote," 1650s as "person who casts a negative vote."

Construction no X, no Y is attested from 1530s (in no peny no pardon). No problem as an interjection of assurance is attested by 1963. No way as a colloquial expression meaning "it can't be done" is attested by 1968 (noway (adv.) "not at all, in no respect, by no means" is from c. 1300). No-knock (adj.) in reference to police raids without permission or warning is by 1970, American English. Phrase no can do "it is not possible" is attested from 1827, a locution of English-speaking Chinese noted 19c. in China, Australia, and the West Coast of the United States.  

We repeated our advice again and again, but got no answer but a loud horse-laugh, and their national maxim of No can do: Europe fashion no do in China. ["Reminiscences of a Voyage to and from China," in Paxton's Horticultural Register, London, 1836]

Middle English bodi, from Old English bodig "trunk of a man or beast; the whole physical structure of a human or animal; material frame, material existence of a human; main or principal part of anything," related to Old High German botah, but otherwise of unknown origin. Not elsewhere in Germanic, and the word has died out in German (replaced by Leib, originally "life," and Körper, from Latin), "but in English body remains as a great and important word" [OED].

The extension to "a person, a human being" is by c. 1300. The meaning "main part" of anything was in late Old English, hence its use in reference to vehicles (1520s). From 1580s as "part of the dress which covers the body."

It is attested from 1590s as "main part of a group, any number of individuals spoken of collectively" and from 1660s as "main portion of a document." Contrasted with soul at least since mid-13c. The meaning "corpse" ("dead body") is from c. 1200. The word was transferred to matter generally in Middle English (as in heavenly body, late 14c.).

Body politic "the nation, the state, whole body of people living under an organized government" is recorded from late 15c., with French word order. Body image was coined 1934. Body count "number of enemy killed in battle or otherwise" is from 1968, from the Vietnam War. Body language is attested from 1967, perhaps from French langage corporel (1966). Body-snatcher "one who secretly disinters the bodies of the recently dead for dissection" is from 1834. Defiant phrase over my dead body attested by 1833.

c. 1793, William Blake's derisive name for the anthropomorphic God of Christianity. The name reflects nobody + daddy.