المستعملة
Actually used.
A word being conventionally assigned to a meaning is distinct from someone's employing it in discourse. An entry in the lexicon, without any occurrence in communication, is not yet an instance of literal or figurative use. This is why the definition specifies use.
The word “faras” is assigned to a horse. Knowing that fact is not itself an occurrence of speech. When “hādhā farasun” is said while pointing to a horse, both the occurrence and its relation to the established assignment can be examined.