P / porrectĭo
noun

porrectĭo

gen. porrectōnis · gender feminine · decl. 3rd
a stretching out; extending; extension
a stretching out, extending, extension: digitorum (opp. contractio), Cic. N. D. 2, 60, 150: bracchii, Auct. Her. 3, 15, 27.—
a straight line
Concr., a straight line (opp. circinatio), Vitr. 10, 3, 8.