Webster’s Revised Unabridged Dictionary · 1913
Proin
Proin (proin), v. t. [See Prune to trim.] To lop; to trim; to prune; to adorn. [Obs.] Chaucer.
The sprigs that did about it grow He proined from the leafy arms. Chapman.
Proin, v. i. To employed in pruning. [Obs.]