What is meant by dime tip and nickel tip?

Answer 1

The roundness of the cue tip. If you hold a nickel or a dime behind a properly shaped tip, you will see it having the same curvature as one of these two in most cases.

A cue tip should be shaped, scuffed, and sides burnished fairly often. Generally, this means before each match. There are tools made for each, and some tools do all three tasks.

The nickel curvature lasts the longest and is the most forgiving, but generally is not intended for the soft tips. Soft tips are intended to give maximum cue ball control and by using the dime tip, allows the tip to stay in contact with the cue ball for the longest period, and also reduce the chance of a miscue farther from center than a nickel tip can.