reciprocal vs similar

reciprocal

adj
  • Mutually interchangeable. 

  • Expressing mutual action, applied to pronouns and verbs; also in a broad sense: reflexive. 

  • Of a feeling, action or such: mutual, uniformly felt or done by each party towards the other or others; two-way. 

  • Done, given, felt, or owed in return 

  • Used to denote different kinds of mutual relation; often with reference to the substitution of reciprocals for given quantities. 

noun
  • A construction expressing mutual action. 

  • The number obtained by dividing 1 by another given number; the result of exchanging the numerator and the denominator of a fraction. 

similar

adj
  • Having traits or characteristics in common; alike, comparable. 

  • Of geometrical figures including triangles, squares, ellipses, arcs and more complex figures, having the same shape but possibly different size, rotational orientation, and position; in particular, having corresponding angles equal and corresponding line segments proportional; such that one can be had from the other using a sequence of rotations, translations and scalings. 

  • Of two square matrices; being such that a conjugation sends one matrix to the other. 

noun
  • That which is similar to, or resembles, something else, as in quality, form, etc. 

  • A material that produces an effect that resembles the symptoms of a particular disease. 

How often have the words reciprocal and similar occurred in a corpus of books? (source: Google Ngram Viewer )