1st_ 'na' is a very colloquial way to say a "no" ( denial). When it is disbelief, the vowel is usually stretched (" Naaa!) , when rejected is used repeatedly ( 'Na , na , na . . . !» ) . She's probably influenced by Englishman nah. 2nd_ 'na' is a colloquial apocope of "nothing". 3rd_ 'na' is a contraction of the archaic Spanish 'enna' ( 'en'). 4th_ 'na' is the internet domain for Namibia. 5th_ 'NA' is the acronym used by the Mexican New Alliance Party. 6th_ 'NA' is the identification of the Narcotics Anonymous organization. 7th_ 'Na' is the symbol of the chemical element sodium (by the Latin name "natrium") . 8th_ 'N sub A' in physics and chemistry is the "Avogadro number", a calculation value for relating molecular mass to weight, which is now redefined as an Avogadro constant. [Note: I can't write it because there is no /A/ subscript letter in Unicode. ]