1. Characterized by straight lines: Since Edward and his wife didn’t like flowery patterns for their wallpaper, they chose colorful one-dimensional, or rectilinear, patterns instead.
2. Etymology: "a straightforward line of descent", from Late Latin rectilineus which comes from the Latin words rectus, "straight" + linea, "line".

A lesser-known variant, "rectilineal", comes from the same Late Latin rectilineus and employs the -al suffix instead of -ar.

Rectilineal still shows up occasionally, but rectilinear is used much more.