Generally treated as non-gradable; comparative and superlative forms are rarely accepted.
Translations
The two companies had parallel strategies for expanding their market share.
Les deux entreprises avaient des stratégies parallèles pour accroître leur part de marché.
The two roads were parallel, running alongside each other for miles without ever meeting.
Les deux routes étaient parallèles, longeant l'une l'autre pendant des kilomètres sans jamais se rejoindre.
Definitions
Extending in the same direction, equidistant at all points, and never converging or diverging. The two roads were parallel, running alongside each other for miles without ever meeting.
Having similar or comparable parts, functions, or characteristics. The two companies had parallel strategies for expanding their market share.
Occurring or existing at the same time or in a similar way; corresponding. The parallel events in the two countries highlighted the global nature of the issue.