1.Definition: (of words) expressing closely related meanings
2.Definition: capable of replacing or changing places with something else; permitting mutual substitution without loss of function or suitability
Related Adjective(s):exchangeable, interchangeable, standardised, standardized
4.Definition: marked by correspondence or resemblance
"Similar food at similar prices", "Problems similar to mine", "They wore similar coats"
5.Definition: resembling or similar; having the same or some of the same characteristics; often used in combination