red supergiant

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A massive star of great size and luminosity that has a relatively low surface temperature ranging from 3,000 to 4,000 kelvin (4,940° to 5,740° F), giving it a reddish or orange hue.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun astronomy A very large, red star, such as Betelgeuse and Antares.