ETYMOLOGY
from Latin rigent-, rigens (stiff, rigid), present participle of rigere (to be stiff)
EXAMPLE
“… An hous [y]maad of aller is but shent;
Yet ther the ground is myre, weet, vnsure,
Pile in aller as for the fundament.
Ek elm & asshe ydried beth rigent,
And while they beth vndried, so curuable,
ffor shippis that they beth right profitable. …”
From: Middle-English translation of Palladius De Re Rustica. ?1440
Edited by Mark Liddell, 1896
Lexicophilia 