chrysal / crissal [ˈkrɪsəl]
chrysal – n. – a transverse line of crushed fibres in the belly of an archery bow beginning as a small crack attacking the weak places, almost imperceptible at the commencement, but which, by degrees, enlarges itself, until it breaks– also called a fret
crissal – adj. – 1. relating to or having a crissum, used chiefly in the vernacular names of birds, the part of the bird surrounding the cloacal opening; 2. the feathers that cover that region; 3. the under tail covers