Unc, XF, VF etc.: Coin grades (used to grade the condition of the coin).
Commemorative: https://en.m.wikipedia.org/wiki/Commemorative_coin
Proof: A type of coin with a special finish, differentiating it from business ("normal") strikes; usually made in sets for collectors. Much more shinier than a normal coin.
Wikipedia has a lot of information,too: https://en.m.wikipedia.org/wiki/Proof_coinage
Pattern: Read this: https://en.numista.com/forum/topic71861.html
Error: Coin that has an error. Here is a picture:
Varieties:
Die crack: Exactly what it sounds, a crack in the die which results in a small ridge of metal on the surface of the coin. Can be of varying sizes.
Off-strike: Again, what it sounds like; a coin struck off-centre on it's planchet. Many coins with slight off-centre strikes can be found, but error collectors usually want more serious ones.
Mule: A coin minted with either the reverse or obverse side not normally seen on the coin.
Rarer terms:
Siege coinage: Coinage minted during a siege. These usually are quite simple. https://en.numista.com/catalogue/pieces52923.html
Emergency coinage: Coin minted during hard times. https://en.numista.com/catalogue/pieces21770.html https://en.numista.com/catalogue/pieces37268.html
Largesse coinage: "During recent centuries, specially prepared coins have been issued to proclaim the coronation of a new monarch. Such coins are known as 'largesse' coins. This type of coins were issued in India during the Mughal era (the 'nisar' coinage), and in Europe in the age of absolutism. In Europe, such coins were scattered from the royal chariot, to achieve attention and applause from the public. In Sweden, coins of this type were issued as late as 1873 (known as 'kastpenning')."
There are 8 Largesse coins on numista. https://en.numista.com/catalogue/pieces111027.html
