What is "similar rectilineal figures"

Similar \Sim"i*lar\, a. [F. similaire, fr. L. similis like, similar. See Same, a., and cf. Simulate.]

1. Exactly corresponding; resembling in all respects; precisely like.

2. Nearly corresponding; resembling in many respects; somewhat like; having a general likeness.

3. Homogenous; uniform. [R.]
   --Boyle.

   Similar figures (Geom.), figures which differ from each other only in magnitude, being made up of the same number of like parts similarly situated.

   Similar rectilineal figures, such as have their several angles respectively equal, each to each, and their sides about the equal angles proportional.

   Similar solids, such as are contained by the same number of similar planes, similarly situated, and having like inclination to one another.