التَّكْسِيرِ
Root: كسر
Full Definition
التَّكْسِيرِ
[The broken plural;] the plural in which the composition of the singular is changed; the change being either apparent, as in رِجَالٌ, pl. of رَجُلٌ, or understood, as in فُلْكٌ, which is both sing. and pl., for the dammeh in the sing. in this case is like the dammeh of قُفْلٌ, and that in the pl. is like that of أسْدٌ.
2 Also تَكْسِيرٌ [The area of a circle]: in the circle are three things: دَوْرٌ [or circumference] and قُطْرٌ [or diameter] and تَكْسِيرٌ [or area], which [last] is the product of the multiplication of the half of the
قطر
by the half of the
دور: and it is sometimes called مِسَاحَةٌ. You say, مَا تَكْسِيرُ دَائِرَةٍ
قُطْرُهَا سَبْعَةٌ وَدَوْرُهَا ٱثْنَانِ وَعِشْرُونَ [What is the area of a circle of which the diameter is seven and its circumference two-and-twenty?]: and the answer is ثَمَانِيَةٌ وَثَلَاثُونَ وَنِصْفٌ [Eight-and-thirty and a half]. [It is scarcely necessary to add that this is not perfectly exact.]
2 Also تَكْسِيرٌ