Voluminous describes something that contains a lot of material or takes up a lot of space. A voluminous book might be 800 pages long and require two hands to hold comfortably. A voluminous report contains so much information that you'd need hours just to read through it all.

When a lawyer reviews voluminous court records, she's facing boxes and boxes of documents. When a historian writes a voluminous biography, the resulting book captures every detail of someone's long and eventful life.

Voluminous can also describe clothing that's deliberately loose and flowing, with lots of fabric. A wizard's voluminous robes billow around him as he walks. A voluminous skirt might be made from yards and yards of material that swirls dramatically when someone spins.

The key idea is abundance: there's a lot of whatever the thing is. Whether it's pages in a book, fabric in a garment, or files in a cabinet, voluminous means impressively large in quantity or size. When your teacher assigns voluminous reading over winter break, you know you'll be spending plenty of time reading.