ne

ne is the negative twin of ut. It introduces purpose and command clauses whose verb goes into the SUBJUNCTIVE: "so that ... not", "that ... should not". After verbs of fearing the logic inverts and catches every beginner out: timeo ne veniat is "I fear that he WILL come", because the thing feared is the thing happening, and timeo ut veniat is "I fear that he will not". It also forms prohibitions (ne feceris) and pairs with quidem for "not even". Keep it apart from the question tag -ne, which is a different animal glued to the end of a word.