being or standing at right angles to the plane of the horizon or a given line or plane
extremely steep; precipitous
(Perpendicular) of, being, or built in a style of Gothic architecture prevalent in England from the late 14th to the 16th cent. characterized by large windows, an emphasis on vertical lines, and sometimes fan vaults
perpendicularity /-ʹlariti/ noun
perpendicularly adv
[Middle English perpendiculer via French from Latin perpendicularis, from perpendiculum plumb line, from per- + pendēre to hang]