"forming a straight line," 1650s, with -ar + rectiline (1560s), from Late Latin rectilineus, from rectus "straight" (from PIE root *reg- "move in a straight line," with derivatives meaning "to direct in a straight line") + linea "line" (see line (n.)). Related: Rectilineal (1640s).
rectilinear patterns in wallpaper
the rectilinear propagation of light
rectangle
rectangular
rectification
rectifier
rectify
rectilinear
rectitude
recto-
recto
rector
rectory
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