rectilinear
adjective /ˌrektɪˈlɪniə(r)/
  /ˌrektɪˈlɪniər/
(specialist)- in a straight line直线的;笔直的 - rectilinear motion直线运动 
 
- rectilinear motion
- having straight lines有直线的 - rectilinear forms直线图形 
 
- rectilinear forms
词源mid 17th cent.: from late Latin rectilineus (from Latin rectus ‘straight’ + linea ‘line’) + -ar.