| Term | Definition |
| megabyte | large unit of computer memory |
| megalith | very large stone used in prehistoric structures in Western Europe |
| megalomania | love of great things; obsession with extravagant things |
| megalopolis | very large city; very large region made up of many cities/towns |
| megaphone | funnel-shaped device used to make the voice larger |
| megalosaur | large dinosaur that lived during the Jurassic Period |
| megastar | very famous person |
| megavitamin | dose of vitamin that provides larger amount of nutrients than required to stay healthy |