What does IMAO mean?
IMAO stands for "in my arrogant opinion."
Where did IMHO come from?
IMAO is an initialism from the internet and text messaging that plays off the earlier IMHO, in which the H (at least in our dictionary) is defined as humble, though usage evidence also sees honest fill the role.
How is IMAO used?
People fond of using IMAO in their texts and on social media might not be aware that it implies that they consider their opinion carries more weight than is warranted. IMAO stands for "in my arrogant opinion," and, well, being arrogant means you have an exaggerated sense of self-importance and tend to make excessive or unjustified claims.
IMAO (that's "In My Arrogant Opinion"), actor-writer Jason Segel and director-writer Nicholas Stoller crafted a sublime romantic soufflé in 2008's Forgetting Sarah Marshall.
— Peter Travers, Rolling Stone, 26 Apr. 2012
There is also the inflated IMMAO ("in my most arrogant opinion"), if you so choose. You might also use IMNSHO ("in my not so humble opinion") if you feel the need to be subtly arrogant.
Words We're Watching talks about words we are increasingly seeing in use but that have not yet met our criteria for entry.