Learn Italian: Non voglio più vedere quel bugiardaccio! - I don't want to see that terrible liar anymore!

Bugiardo means "liar" (or the adjective "untruthful"). The suffix -accio is pejorative—it adds a strong sense of negativity, badness, or contempt. By dropping the final -o of the root word and adding -accio, we get bugiardaccio, which translates to a "terrible liar," "dirty liar," or "awful liar."

Is bugiardaccio acting as a noun or an adjective here?

Here it's acting as a noun ("that terrible liar"). The suffix -accio is highly versatile: it can attach to adjectives to make them sound worse (like cattivo to cattivaccio), but it can also attach directly to nouns to express disgust or disdain (like libro to libraccio, meaning a trashy or ruined book). Since bugiardo can function as both a noun and an adjective, it takes the suffix perfectly here.

Why do we use quel instead of quello before bugiardaccio?

The demonstrative adjective quello (that) changes its ending to mimic the definite article that the following word would take. Because bugiardaccio is masculine, singular, and starts with a simple consonant (b), it would take the article il. Therefore, quello changes to its il-matching form, which is quel.

Could I put at the end of the sentence instead: ?