- vertical
- vertical, perpendicular, plumb can mean situated at right angles to the plane of the horizon or extending from that plane at such an angle.Vertical suggests a relation to the vertex or topmost point (see APEX 1); it is used most often when the thing so described actually extends upward from the plane of the horizon or from its base or support in such a direction that if its direction line were produced, it would reach the zenith{
vertical threads in atapestry
}{a vertical piston
}{walls not quite vertical
}Vertical is, of these terms, the most frequently applied to abstractions and the most common in extended use{the vertical organization of society
}Perpendicular differs from vertical in being normally applied to things that extend upward or downward from the horizontal or both upward and downward; thus, one looks up or down the perpendicular face of a cliff{a perpendicular fall of water
}Consequently, perpendicular is used more often than vertical to suggest little more than precipitousness or extreme steepness or stiffness and straightness of line{a perpendicular descent
}{a stiff perpendicular old maid— Mitford
}Plumb is largely a builder's term used particularly in judging the exact verticality or perpendicularity of something by its conformity to the direction of a plumb line{the wall was plumb
}Antonyms: horizontal
New Dictionary of Synonyms. 2014.