Choose the word which is different from the rest.

The answer is D. Terrible.

A. Medium is a word that means “of a moderate or average size, amount, or degree.”
B. Average is a word that means “a number expressing the central or typical value in a set of data, in particular the mean, median, or mode.”
C. Mediocre is a word that means “of only moderate quality; not very good.”
D. Terrible is a word that means “extremely bad or unpleasant.”

The word “terrible” is different from the rest of the words in the list because it is the only word that has a negative connotation. The other words all have neutral or positive connotations.