1. An abbreviation for "in my humble opinion," used to present one's viewpoint or beliefs with an awareness or cautiousness that the listener might disagree or be offended. IMHO that paint color doesn't work for the room, but then again, green isn't my favorite color.

2. An abbreviation for "in my honest opinion," used to present one's true and/or unfiltered beliefs. The use of this abbreviation to indicate this meaning (as opposed to the traditional meaning found in Definition 1) likely arose due to the prevalence of other abbreviations in which "H" stands for "honest" (e.g. "TBH," meaning "to be honest"). That green paint color doesn't work in that room IMHO. What about a nice gray?