nec

"nec" and "neque" are the same word, and Roman writers pick between them mostly for sound, with "neque" preferred before a vowel. Either one is "et non" fused into a single word, so it means "and not" and does the work of joining and negating at once. Latin does not normally write "et non".

Doubled, it gives "nec ... nec ..." or "neque ... neque ...", neither ... nor. Mixed with a positive it can pair as "neque ... et ...", meaning "not only not ... but also". Note also "nec quisquam" and "nec quicquam", the standard ways of saying "and nobody" and "and nothing", since Latin will not stack "nec" with "nemo" or "nihil".