[noun] (architecture) a masonry construction (usually curved) for spanning an opening and supporting the weight above it
[verb] form an arch or curve; "her back arches"; "her hips curve nicely" Synonyms:curve, arc
[adjective] (of persons) highest in rank or authority or office; "his arch rival"
[adjective] (used of behavior or attitude) characteristic of those who treat others with condescension Synonyms:condescending, patronizing, patronising
[adjective] expert in skulduggery; "an arch criminal"