To cut or trim (fingernails); to cut the rough edges off of s.t. (as a newly woven mat); to trim (as a hedge).
If the object is one's nails then there is no need to mention the nails and no affixation is used.
We use a knife for cutting (nails).
It is believed by some that if you cut your nails at night you will not have a long life. It is also believed that if you cut your nails on Friday you will receive a big blessing/reward.