nippy

nippy - a little cold

nit-pick

argue about small, unimportant detail

no spring chicken

no sweat

no sweat - easily done, no problem

no-brainer

something which makes absolutely no sense

nocturnal

nocturnal - used for animals that are out and about at night

nod off

to nod off - fall asleep

nose-dive

a nose-dive - a very sudden drop or decline

Not very helpful!!

now and then

now and then - sometimes