- (a.) Hence: Monstrous; prodigious; wonderful; dreadful; as, a beast of portentous size.
- (a.) Of the nature of a portent; containing portents; foreshadowing, especially foreshadowing ill; ominous.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). portentous. Retrieved September 26, 2026, from http://smartdefine.org/portentous/definitions/2047658 |
| Chicago | Webster's. 2011. "portentous" http://smartdefine.org/portentous/definitions/2047658 (accessed September 26, 2026). |
| Harvard | Webster's 2011, portentous, Smart Define, viewed 26 September, 2026, <http://smartdefine.org/portentous/definitions/2047658>. |
| MLA | Webster's. "portentous" 27 May 2011. Web. 26 September 2026. <http://smartdefine.org/portentous/definitions/2047658> |