Noun

• S: (n) arch (a curved shape in the vertical plane that spans an opening)
• S: (n) arch (a curved bony structure supporting or enclosing organs (especially the inner sides of the feet))
• S: (n) arch, archway (a passageway under a curved masonry construction) "they built a triumphal arch to memorialize their victory"
• S: (n) arch ((architecture) a masonry construction (usually curved) for spanning an opening and supporting the weight above it)

Verb

• S: (v) arch, curve, arc (form an arch or curve) "her back arches"; "her hips curve nicely"

Adjective

• S: (adj) arch, condescending, patronizing, patronising ((used of behavior or attitude) characteristic of those who treat others with condescension)
• S: (adj) arch, impish, implike, mischievous, pixilated, prankish, puckish, wicked (naughtily or annoyingly playful) "teasing and worrying with impish laughter"; "a wicked prank"