Definition of "megalith" [meg•a•lith]

• A very large stone used in various prehistoric architectures or monumental styles, notably in western Europe during the second millennium B.C. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Plaid Cymru should use its position in government to oppose the building of the Severn Barrage "megalith", the editor of a Welsh language green magazine has told Golwg."
• "So maybe the megalith is another harbinger, and it’s all pointing toward your apocalyptic vision, the arrival of the major big bad."
• "As we speak, one giant telecommunications company, the cable/programming megalith Comcast, is poised to take over another, the NBC network of local stations, cable channels and even a movie studio."