With respect to futures contract, it is the situation where the maturity of the futures and that of the underlying...

The risk that arises in case of hedging an asset with another using futures while the two are not identical...

Hedging a cash (spot) commodity or security with a futures contract where the underlying commodity is similar but not identical...

A situation that arises when the risk associated an asset is to be hedged but there is no futures contract on that...