"similar" is referenced in the pages listed below.

Similar triangles - ratio of areas is the square of the ratio of the sides.
Similar triangles - all three corresponding angles the same. AAA
Definition and properties of similarity
Similar triangles - all three sides in same proportion. SSS
Definition and properties of similar triangles - testing for similarity
Similar triangles - two sides in same proportion, included angle the same. SAS
Similar triangles - sides, medians, perimeters, altitudes all in same proportion.