giant sequoia

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

• noun A very tall, coniferous evergreen tree (Sequoiadendron giganteum) native to the high western slopes of the Sierra Nevada in California and having a massive trunk and light-colored, reddish wood.

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

• proper noun the USDA-preferred name for the species Sequoiadendron giganteum
• proper noun any of the trees belonging to this species, but especially the large and mature trees.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun extremely lofty evergreen of southern end of western foothills of Sierra Nevada in California; largest living organism