curvilinear
cur.vi.lin.ear or cur.vi.lin.eal \.k*r-v*-'lin-e--*r\ \-e--*l\
\-.lin-e--'ar-*t-e-\ aj [L curvus + linea line] 1: consisting of or bounded
or represented by a curved line 2: marked by flowing tracery {~ Gothic} -
cur.vi.lin.ear.i.ty n
Webster's English Dictionary