Definition of "portentous" [por•tent•ous]

• Of the nature of or constituting a portent; foreboding: "The present aspect of society is portentous of great change” ( Edward Bellamy). (adjective)
• Full of unspecifiable significance; exciting wonder and awe: "Such a portentous and mysterious monster roused all my curiosity” ( Herman Melville). (adjective)
• Marked by pompousness; pretentiously weighty. (adjective)

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.

• "Harris's great skill lies in pulling back every time her creation veers towards the portentous, that is to say the Tolkienesque ...."
• "The decision to allow infant baptism is described as portentous: a dramatic sign which foreshadows something."
• ""Yes, this has been what you might call a portentous evening," agreed"