Learn Italian: La strega cattiva diceva brutte parole al lupo. - The bad witch said bad words to the wolf.

The verb dire (to say/tell) is irregular. Its imperfect forms are actually built from its original Latin root, "dicere". To form the imperfect, you take that old root, drop the "-re", and add the regular endings: io dicevo, tu dicevi, lui/lei diceva, and so on.

Could I use "ha detto" instead of "diceva" in this sentence?

It depends on the context! Using the imperfect tense (diceva) means this was an ongoing or repeated action in the past—she used to say bad words to the wolf, or she was saying them over a period of time. If she said a bad word just once and the action was completely finished, you would use the passato prossimo: ha detto.

Why does cattiva go after the noun, but brutte goes before it?

Most descriptive adjectives in Italian go after the noun, which is why we say la strega cattiva (the bad witch). However, a small group of very common adjectives relating to beauty, age, goodness, and size (like bello, brutto, buono, vecchio) usually go before the noun. That is why it is brutte parole.

How is al lupo formed?