With the root k-b-r, the complete textbook eight-slot paradigm is:
Word / formMeaning / explanation
أَكْبَرُone greater/bigger male.
أَكْبَرَانِtwo greater males.
أَكْبَرُونَmasculine sound plural.
أَكَابِرُeminent/great persons; masculine broken plural.
كُبْرَىone greater feminine entity.
كُبْرَيَانِfeminine dual.
كُبْرَيَاتٌfeminine sound plural.
كُبَرٌa second feminine plural pattern.
These are paradigm forms; real-world idiomatic frequency varies across entries.