antiparallel

American  

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

adjective

Mathematics, Physics.

1. (of two vectors) pointing in opposite directions.

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antiparallel British  

/ ˌæntɪˈpærəˌlɛl /

adjective

1. physics parallel but pointing in the opposite direction

2. maths (of vectors) parallel but having opposite directions

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Etymology

Origin of antiparallel

First recorded in 1650–60; anti- + parallel

Example Sentences

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

Class 6 contains antiparallel, face-to-back, up–up structures; class 7 contains antiparallel, face-to-face up–down structures; and, class 8 contains antiparallel, face-to-face, up–down structures.

From Nature • Nov. 8, 2016

The spins of the u and d quarks are antiparallel, enabling the pion to have spin zero, as observed experimentally.

From Textbooks • Aug. 12, 2015