أن يكون صدق ذلك المعنى على سائر أفراده على سبيل الاستواء
Its meaning applies to all of its instances on an equal footing.
Such a general term is called mutawāṭiʾ (univocal in predication). “Human,” for instance, applies to Zayd, ʿAmr and Bakr as humans without degrees of humanity. One may be more knowledgeable or stronger, but that does not make the term “human” apply to him in a greater degree.
Equality concerns the predication of this particular universal meaning, not equality in every property, achievement or condition.