FACEPALM
Etymology
Noun
facepalm (plural facepalms)
A gesture of bringing one or both palms to the face, with various interpretations.
Coordinate terms
• headslapper
Verb
facepalm (third-person singular simple present facepalms, present participle facepalming, simple past and past participle facepalmed)
To bring the palm of one’s hand to one’s face as an expression of mixed humor and disbelief, disgust or shame; for example, when one is caught off-guard with a particularly bad pun.
To bring one’s face down to one’s cupped hand or hands.
Usage notes
• Found primarily in real-time text communication on the Internet, often involving image macros or ASCII art of someone facepalming.
Coordinate terms
• smack one's forehead
Source: Wiktionary