Definitionen
1.InterjectionDraws attention to an act of foolishness or stupidity."I put chips in my soup instead of crackers. Derp."
2.InterjectionA placeholder for unimportant details, blah blah blah.
3.VerbTo act stupidly or foolishly.
4.VerbTo make a stupid mistake.
5.VerbTo have one's eyes pointing in different directions; to exhibit strabismus.
6.NounA person who acts stupidly or foolishly; a person who derps.
7.NounA stupid mistake, stupidity.
8.NounThe constant repeating of an opinion after facts have proved it incorrect, especially as a rhetorical tactic.