Why are these trees called deciduous?

After turning shades of yellow, orange, and red, deciduous trees shed their leaves. Trees such as birch, oak, and maple lose water quickly from their wide, flat leaves. In wintertime, it is hard for them to absorb water from the cold, often frozen ground, so they die and fall off. In the springtime, leaf and flower bud return, burst open, and come into full foliage by summer.