antiparallel

American

[an-tee-par-uh-lel, an-tahy-] / ˌæn tiˈpær əˌlɛl, ˌæn taɪ- /

adjective

Mathematics, Physics.

(of two vectors) pointing in opposite directions.

antiparallel British

/ ˌæntɪˈpærəˌlɛl /

adjective

physics parallel but pointing in the opposite direction
maths (of vectors) parallel but having opposite directions

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of antiparallel

First recorded in 1650–60; anti- + parallel

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

antiparallel

Wilson continued, "If those magnetic moments interact in a way that wants them to point antiparallel to one another, we call that antiferromagnetism."

From Science Daily ● Mar. 16, 2026

The two strands run antiparallel to each other.

From Textbooks ● Jun. 9, 2022

On rare occasions the spins of the protons and electrons in neutral hydrogen atoms flip from being parallel to antiparallel, emitting a photon at a frequency of 1.4 gigahertz—the so-called 21-centimter radiation.

From Science Magazine ● Jul. 18, 2019

The two strands of DNA’s double helix run antiparallel, or in opposite directions.

From Textbooks ● Jan. 1, 2018

Whether the β-strands in a β-sheet are parallel or antiparallel to each other, they are generally in register.

From Nature ● Nov. 8, 2016

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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023