«الاستخدام: ذكر اللفظ بمعنى وإعادة ضميرٍ عليه بمعنى آخر»
Istikhdam mentions a word in one sense and subsequently refers to it by a pronoun intended in another sense.
Another form employs two pronouns referring back to the same expression but requiring different senses. The formal antecedent stays the same, whereas the intended semantic value changes.
This shift is what distinguishes istikhdam from ordinary anaphora and simple tawriyah.