Other forms: parallels, paralleling, paralleled
Two lines are parallel when they run side by side, always the same distance apart, and never meet however far you draw them. Railway tracks running to the horizon, the ruled lines on a page, two cars in parallel lanes of a motorway.
Away from geometry, parallel means happening at the same time and in a matching way: parallel investigations, a parallel career, two systems running in parallel for a month. As a noun a parallel is a similarity between two separate things, and you draw a parallel between them — learn that phrase whole. A parallel is also a line of latitude, which is how the 38th parallel ended up in the news. The spelling catches everyone: one r, then two ls, then one l. The verb breaks the usual British doubling rule as well, so it is paralleled, with a single l.
1adjectiveparallelRunning side by side at the same distance apart, never meeting.
“The two roads run parallel for a mile and then split.”
2adjectivehappeningHappening at the same time and in a similar way.
“A parallel inquiry was under way in Germany.”
3nounsimilarityA similarity between two separate things.
“There are clear parallels between the two crashes.”
4verbmatchTo be similar to something, or to match it closely.
“His rise paralleled the growth of the company.”
5nounlineA line of latitude, marking distance north or south of the equator.
“The border follows the 49th parallel for a thousand miles.”
Parallel came through Middle French parallèle from Latin parallēlus, and the Latin is Greek in disguise: para-, 'beside', joined to a word meaning one another. So parallel lines are literally beside each other, and the meaning has not shifted in two thousand years.
Latin
parallēlus,parallēlos
Middle French
parallèle
English, today
parallel
From Middle French parallèle and its etymon Latin parallēlus,parallēlos. The verb is from the noun. See also para- and allo-.
Etymology from Wiktionary, CC BY-SA