substantiative
1. [ adjective ] serving to support or corroborate
Synonyms: confirmative confirming confirmatory corroborative corroboratory substantiating validating validatory verificatory verifying collateral
Examples:

"collateral evidence"

Related terms: supportive
Similar spelling:   substantive
  substantiate
  substantiated
  substantiation
  substantiating
  substantive_dye
  substantial
  substantival
  substantialness
  substantia_alba
  substantially
  substantia_nigra
  substantiality
  substantia_grisea
  substitution
  substituting