Perpendiculars

Part of speech: noun

Definitions

1. Two distinct lines or surfaces that intersect to form a right angle
2. The condition of being positioned at an angle of ninety degrees relative to one another
3. Lines or planes that meet forming a 90-degree angle ; the arrangement of something at an exact right angle to another

Etymology: "Perpendiculars" is the plural of "perpendicular," which in its adjective and noun senses comes from Latin "perpendiculum," a plumb line or plumb bob. The Latin word combined "per-" (through, thoroughly) with "pendere" (to hang), describing a weight hanging straight down on a string. Because a plumb line hangs vertically, it sets a perfectly upright reference, and English adopted the term for lines and surfaces meeting at a right angle. The noun plural refers to such pairs of lines or planes, and the sense of "at right angles" is the original geometric meaning carried over from the plumb line's vertical direction. The word thus preserves a physical object: a weighted cord that marks true vertical.

Synonyms: orthogonal, vertical, right-angled