"The cold is not through her."
Translation:Níl an fuacht tríthi.
I'm a native English speaker, and the phrase "The cold is not through her" seems a bit opaque to me. Is this "cold" as in the illness, or the state of being cold, or what?
Níl is the negative form of tá. You use ní as the negative form of the copula and the negative particle in the present, future, and some irregulars (6 of them) in the past tense.
And, if you look etymologically, ní is actually in níl. It was once ní fhuil, but <fh> is silent in Irish, so it condensed to Níl.