If 'quartered' means the object has been divided into four, which word do we use for an object that's been divided into 5?

Halved and quartered are really the only words like that. You just don't see thirded, fifthed, and such. XD

Try things that say something has been divided into fifths. Torn into five pieces, separated into fifths, etc.

Of course, you can use the fraction = one fifth.

thankyou!!! but what about 'cinqued'?? cinqe is an old english word for 5, isn't it?

The word you would use for an object that has been divided into five parts is "quintupled." However, it's important to note that "quintupled" typically refers to multiplying something by five, rather than dividing it into five equal parts. If you specifically want to indicate dividing something into five parts, you could use the word "split" or "divided into fifths."