facetious
adjective

- trivially or inappropriately humorous.

(Oxford Compact Dictionary)

---
WORD ORIGIN

Etymology: borrowed from the French facetieux (a joke) and from the Latin facetus, which evolved from the Latin fax (torch, light, falling star). The adjective facetus originally meant shining, gracious, but later adopted the sense of witty, spirited.

When is something funny and when is it facetious? It’s a fine line without any hard and fast rules. Although some dictionaries also define facetious as simply "humorous, funny", it’s mostly used as a disapproving term to describe being funny when it’s not appropriate. The question is, when is humour appropriate?

You might say that like beauty, humour "is in the eye of the beholder." What seems comical and entertaining to one person might be offensive to another, particularly when it’s related to things like religion. Even in countries where freedom of speech is protected by the constitution, taking a few jabs at religious figures can inflame passions and lead to serious consequences.

Former United States Supreme Justice Robert Jackson put it this way: "The price of freedom of religion, or of speech, or of the press, is that we must put up with a good deal of rubbish."

---
SYNONYMS

amusing, blithe, capering, comic, comical, droll, farcical, flippant, frivolous, funny, gay, humorous, indecorous, ironic, irreverent, jesting, jocose, jocular, joking, joshing, laughable, ludicrous, merry, not serious, playful, pleasant, punning, ridiculous, salty, sarcastic, satirical, tongue-in-cheek, waggish, whimsical, wisecracking, witty, wry

---
ANTONYMS
formal, grave, lugubrious, serious, sober, sombre

---
PRACTICE OWAD in a conversation
say something like:

"It irritates me when people are FACETIOUS, especially during serious discussions."