ṣadr
صَدْر
the first half of a line of verse; chest
يُكتب صدر البيت على اليمين وعَجُزُه على اليسار.
The first half of the line is written on the right, the second half on the left.
شعر العدّاء بضيق في صدره بعد السباق.
After the race, the runner felt a tightness in his chest.