The term 'hardware bit' refers to a small piece of metal used in construction and carpentry. The two crossword solutions for this term are TNUT (4 letters) and NAIL (4 letters). TNUT is an abbreviation for t-nut, which is a type of nut with a long, thin body and a flange at one end. It is used to secure items to a surface by inserting it into a pre-drilled hole and then tightening a bolt or screw. A NAIL is a thin metal rod with a pointed tip that is driven into a surface to hold two objects together. Nails are commonly used in carpentry and construction.