corroboration (n.) Look up corroboration at Dictionary.com
mid-15c., "strengthening, support," from Late Latin corroborationem (nominative corroboratio), noun of action from past participle stem of Latin corroborare "to strengthen, invigorate," from assimilated form of com "with, together," here perhaps as "thoroughly" (see com-) + roborare "to make strong," from robur, robus "strength," (see robust). Meaning "confirmation" attested by 1768.