Answer: perpendicular

AnswerCrossword Clue
PERPENDICULARVertical
perpendicularAt an angle of 90░ to a given line, plane, or surface
perpendicularat right angles to a line or plane / a perpendicular line
perpendicularDenoting the latest stage of English Gothic church architecture, prevalent from the late 14th to mid 16th centuries and characterized by broad arches, elaborate fan vaulting, and large windows with vertical tracery
perpendicularAt an angle of 90░ to the ground; vertical
perpendicular(of something with a slope) So steep as to be almost vertical