A "steaming basket" refers to a container used in cooking that is placed inside a pot or pan with boiling water. It is used to cook food by trapping the steam, which cooks the food without it being directly in contact with the boiling water.
I already had a simple steam basket that I use inside pots for steaming veggies. (iloveclothdiapers.com)
To help use the steam setting, this Japanese rice cooker includes a BPA - free steaming basket, as well as a rice measuring cup, nonstick rice spatula, and spatula holder. (geekwrapped.com)