وَالثَّالِثَةُ بِالِالْتِزَامِ لِكَوْنِ الْخَارِجِ لَازِمًا لِلْمَوْضُوعِ لَهُ
The third is implication, because the indicated matter lies outside the established meaning while having a necessary connection to it.
In a traditional logical illustration, the capacity for laughter is a special property linked to insān. It is not part of the essential definition “ḥayawān nāṭiq” but is traditionally treated as following from that kind of being; hence it exemplifies an external concomitant.
“Capable of laughter” does not mean that every human being is laughing at every moment. The requirement of necessity raises a further question: what kind of connection between a meaning and its concomitant must the mind recognize?