संगत —    सुसंगत —

संगत  f) company; accompaniment; a) relevant; logical, rational; compatible

असंगत  a) alien, illogical, improper, inappropriate, incoherent

संगति  m) company, association; consistency/consistence; compatibility; rationality; coherence, harmony; relevance 

सुसंगत  a) very appropriate/logical, valid/tenable [sostenible]/reasonable; concordant (concordante, armónico); relevant (pertinente) 

सु  prefix imparting the meanings of good, beautiful, pretty, excellent, thorough (total, verdadero, absoluto, exhaustivo), well, easy, etc.