What does the word facetiously mean?

treating serious issues with deliberately inappropriate humor; flippant.

Facetiously means anything that is said without actually intending to be taken literally or seriously.

Explanation:

The word "facetiously" is an adjective that is used when describing a person or anything which should not be taken in the literal sense. It is not meant to be taken in a serious manner, kind of like a 'white lie'.

Supposing a person said something abut another person, or talks to that other person in a facetious manner, then it means that what he / she said is not serious and should not be treated or taken literally. It can also even be said or implied in an amusing and humorous way, lacking any serious intent / content.