والمعرّف بلام العهد والإضافة
And the subject made definite through the article of prior reference or through annexation.
The article of prior reference (لام العهد) points the listener toward a known or determinate referent. Annexation (الإضافة) can identify a noun through its relation to a definite noun or pronoun when the construction is of the defining kind.
In «جَاءَ الرَّجُلُ», ‘the man’ might refer back to a person mentioned earlier. In «جَاءَ غُلَامُ زَيْدٍ», the servant is identified through his relation to Zayd. The rhetorical question is not just whether «ال» or two linked nouns appear, but how the listener recovers the intended referent.