A bassinet is a small basket used as a bed for a baby. A bassinet is portable, making it easy to carry the baby around.
The et ending in bassinet is a clue that this is something small, specifically a small basket used for carrying a baby. The baby also can sleep in the bassinet. Like baby clothes, the bassinet will be quickly outgrown, but it's very helpful for awhile. A bassinet is a common present for a mother to receive at a baby shower. Awwww.