What is the linking verb violinist usually sound terrible?

The linking verb in the sentence "Violinists usually sound terrible" is sound.

Here's why:

* Linking verbs connect the subject of a sentence to a word or phrase that renames or describes the subject.

* In this sentence, "violinists" is the subject, and "terrible" is the predicate adjective describing the violinists.

* The verb "sound" acts as a link between the subject (violinists) and the adjective (terrible), showing the state or condition of the violinists.

Note: While "usually" is an adverb modifying the verb "sound," it doesn't play the role of a linking verb.