overarch

from WordNet (r) 3.0 (2006)

overarch
    v 1: be central or dominant; "This scene overarches the entire
         first act"
    2: form an arch over; "Big rocks overarch the stream" [syn:
       {overarch}, {arch over}]

from The Collaborative International Dictionary of English v.0.48

Overarch \O`ver*arch"\, v. t. & i.
   To make or place an arch over; to hang over like an arch.
   "Brown with o'erarching shades." --Pope.
   [1913 Webster]

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