perpendicular vs rectangular

perpendicular is a noun but rectangular is not a noun.

Word	Noun	Adjective	Verb	Adverb
perpendicular	Yes	Yes	No	No
rectangular	No	Yes	No	No

perpendicular (noun)	rectangular (noun)
an extremely steep face
a cord from which a metal weight is suspended pointing directly to the earth's center of gravity; used to determine the vertical from a given point
a Gothic style in 14th and 15th century England; characterized by vertical lines and a four-centered (Tudor) arch and fan vaulting
a straight line at right angles to another line

perpendicular (adjective)	rectangular (adjective)
intersecting at or forming right angles	having four right angles
at right angles to the plane of the horizon or a base line	having a set of mutually perpendicular axes; meeting at right angles
so steep as to be nearly vertical