Is a nickel considered to be a coin?

Answer 1

In popular usage, a nickel IS a coin even though its name is technically "5 cent piece".

The name dates back to the mid-1800s when nickel was first used in making US Coins. At that time the Mint issued 3-cent and 5-cent coins made of silver. When it became practical to use nickel metal in coins, the Mint also struck the same denominations in an alloy of copper and nickel. The two different compositions circulated together for a number of years; to distinguish them from their silver counterparts people called both nickel-based coins "nickels", adding the denomination: 3-cent nickels and 5-cent nickels.

Eventually the Mint discontinued production of both three-cent coins and silver five-cent coins, leaving only so-called "5-cent nickels" in circulation. Because there was no longer any need to distinguish denominations, people dropped the "5-cent" modifier in ordinary conversation and the coins simply became "nickels".