What does parallelogram mean?
A parallelogram is a four-sided geometric figure in which both pairs of opposite sides are parallel. This structure gives it several predictable properties: opposite sides have equal lengths, opposite angles are equal, and adjacent angles add up to 180 degrees. A rectangle is therefore a special kind of parallelogram, as is a rhombus, although most parallelograms have neither right angles nor four equal sides. The word is also used informally for objects or designs with a similar slanted, elongated shape, such as a parallelogram-shaped panel or mark. In mathematics, parallelograms are important because their opposite sides can be moved to create equivalent shapes, including rectangles, which helps with area calculations and proofs. The term comes from Greek roots meaning “parallel” and “line,” reflecting the defining feature that the figure is bounded by two pairs of parallel lines.
nounA quadrilateral with two pairs of opposite sides parallel. In a parallelogram, opposite sides are equal in length and opposite angles are equal.
- A quadrilateral with two pairs of opposite sides parallel.
"The artist drew a parallelogram from two pairs of carefully measured parallel lines."
"The parallelogram has equal opposite sides and equal opposite angles."
"She transformed the rectangle into a parallelogram by shifting its upper pair of sides sideways."
The regular plural adds -s; in general use, parallelograms refers to multiple geometric figures or similarly shaped objects.
"Several parallelograms appear in the geometric pattern."
A parallelogram is the geometry of opposite sides: the two sides facing each other never meet, no matter how far the shape is extended.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does parallelogram come from?
The word comes from Greek parallēlogrammon, a term formed from parallēlos, “parallel,” and gramma, “line” or “letter.” It entered English through Latin and ultimately referred to a quadrilateral bounded by two pairs of parallel lines. Its relatives include parallel, parallelism, and parallelepiped, all of which share the Greek element parallēlos.
How parallelogram is actually used
In general usage, the term is primarily mathematical. In art, architecture, and design, it may describe any roughly four-sided form whose opposite sides appear parallel.
Easily confused with parallelogram
A parallelogram has two pairs of parallel opposite sides, whereas a trapezoid has only one pair of parallel opposite sides.
A rectangle is a parallelogram whose four angles are right angles, while a parallelogram may have acute and obtuse angles.