Emily Dickinson Lexicon

PER-PEN-DIC'U-LAR, a. [L. perpendicularis, from perpendiculum, a plumb line; perpendeo; per and pendeo, to hang.]

1. Hanging or extending in a right line from any point toward the center of the earth or of gravity, or at right angles with the plane of the horizon.
2. In geometry, falling directly on another line at right angles. The line A is perpendicular to the line B.