The phrase "arching roofline" refers to a design features where the roof of a building curves like a gentle arch from one side to the other, rather than being a straight line or slope. Full definition
Attractive headlight arrays and an aggressive, arched roofline give the FX plenty of style. (autolist.com)
Aft of the coupe - style front end — with its wider, flatter grille — the TT Sportback shares fastback styling cues with that of Audi's A5 and A7 Sportbacks, though features like the wide wheel arches and arched roofline hark back to, in Audi's words, «the TT's formal idiom». (evo.co.uk)
It's attractive and understated, almost classic now, with its iconic arching roofline. (cars.com)