/ ˈkɜːvətʃə(r); NAmE ˈkɜːrv-/ noun
[ U ] ( technical ) the state of being curved; the amount that sth is curved :
the curvature of the earth
curvature of the spine
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WORD ORIGIN
late Middle English : via Old French from Latin curvatura , from curvare to bend, from curvus bent.