"quality of being relevant to the matter in hand," 1590s, from stem of Latin pertinens "pertaining," present participle of perinere (see pertain) + -cy.
Entries linking to pertinency
pertain v.
early 14c., perteinen, "be attached legally," from Old French partenir "to belong to" and directly from Latin pertinere "to reach, stretch; relate, have reference to; belong, be the right of; be applicable," from per "through" (from PIE root *per- (1) "forward," hence "through") + tenere "to hold" (from PIE root *ten- "to stretch").
From late 14c. as "to belong to as a possession or an adjunct; belong to as one's care or concern," also "have reference to." Related: Pertained; pertaining.
-cy
abstract noun suffix of quality or rank, from Latin -cia, -tia, from Greek -kia, -tia, from abstract ending -ia (see -ia) + stem ending -c- or -t-. The native correspondents are -ship, -hood.