Origins
The word 'not' is the primary negator in Modern English, but it was not always so.βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ Its history illustrates one of the most celebrated patterns in historical linguistics: Jespersen's Cycle, named after the Danish linguist Otto Jespersen, who first described how negation markers weaken, get reinforced, and are eventually replaced by their own reinforcement.
Old English negated verbs with the preverbal particle 'ne': 'ic ne wΔt' (I don't know), 'hΔ ne cΕm' (he didn't come). This was the inherited PIE negation strategy β a simple particle *ne placed before the verb, preserved also in Latin 'nΕn' (from 'ne Ε«num,' not one), Greek 'ne-' (as in 'nekrΓ³s,' not living β dead), and Sanskrit 'na' (not). Over time, the monosyllable 'ne' became phonologically weak, and speakers began reinforcing it with an emphatic noun phrase: 'ic ne wΔt nΔwiht' (I don't know nothing β I don't know a thing). 'NΔwiht' is a compound of 'nΔ' (no, never, from 'ne' + 'Δ,' not ever) + 'wiht' (thing, creature, from Proto-Germanic *wihtiz).
During the Middle English period, this reinforcement became obligatory. By the 13th century, 'ne' was being dropped from negated sentences, and the erstwhile emphatic 'nΔwiht' β reduced through centuries of unstressed pronunciation to 'noht,' 'not' β became the sole negation marker. The reinforcement had replaced the original.
Middle English
French underwent an almost identical process. Old French negated with 'ne' alone. Speakers began adding emphatic minimizers: 'je ne marche pas' (I don't walk a step), 'je ne vois point' (I don't see a point), 'je ne mange mie' (I don't eat a crumb). In Modern French, 'pas' has become the primary negator, and 'ne' is routinely dropped in speech: 'je sais pas' (I don't know). French is currently at the same stage of the cycle that English reached in the 14th century.
German 'nicht' is a direct cognate of English 'not,' from the same Old Germanic compound *ne + *wihtiz (not a thing). Dutch 'niet' shows the same origin. In all three languages, the word for 'not' literally means 'no thing,' and in all three, it replaced an earlier simple negator 'ne' through the same reinforcement cycle.
The English negative family is extensive. 'No' is from Old English 'nΔ' (not ever). 'None' is 'not one.' 'Nothing' is 'not a thing' β a later compound that recapitulates the very process that created 'not' itself. 'Never' is 'not ever.' 'Neither' is 'not either.' 'Nor' is 'not or.' Each of these words carries the PIE negator *ne in its first syllable, making the /n-/ onset one of the most reliable markers of negation in the language.