nihil ad rem (L.), nothing to the point.
nihil tetigit quod non ornavit, or nullum quod tetigit non ornavit (L.), he touched nothing without adorning it.
nil admirari (L.), to wonder at nothing, to admire nothing, to be superior and self-complacent.
nil desperandum (L.), never despair.
n'importe (Fr.), it matters not.
nisi Dominus frustra (L.), unless the Lord [build the house, they labour] in vain [that build it]—the motto of Edinburgh.
nisi prius (L.), unless previously—a name [from the first words of the writ] given to the jury sittings in civil cases.
nitor in adversum (L.), I strive against adverse circumstances.
noblesse oblige (Fr.), rank imposes obligations.
nolens volens (L.), whether he will or not.