Webster's 1828 Dictionary
CURVILINEAR, CURVILINEAL
a.[L., bent and a line. ] Having a curve line; consisting of curve lines; bounded by curve lines; as a curvilinear figure.
CURVILINEARITY
n.The state of being curvilinear, or of consisting in curve lines.
Webster's 1913 Dictionary
CURVILINEARITY
CURVILINEARITY Cur `vi *lin `e *ar "i *ty (-r "-t ), n.
Defn: The state of being curvilinear or of being bounded by curved lines.
CURVILINEARLY
CURVILINEARLY Cur `vi *lin "e *ar *ly (-r-l ), adv.
Defn: In a curvilinear manner.
New American Oxford Dictionary
curvilinear
cur vi lin e ar |ˌkərvəˈlinēər ˌkərvəˈlɪniər | ▶adjective contained by or consisting of a curved line or lines: these designs employ flowing, curvilinear forms. DERIVATIVES cur vi lin e ar ly adverb ORIGIN early 18th cent.: from curvi- ‘curved, ’ from Latin curvus, on the pattern of rectilinear .
Oxford Dictionary
curvilinear
curvilinear |ˌkəːvɪˈlɪnɪə | ▶adjective contained by or consisting of a curved line or lines: these designs employ flowing, curvilinear forms. DERIVATIVES curvilinearly adverb ORIGIN early 18th cent.: from Latin curvus ‘bent, curved ’, on the pattern of rectilinear .