Corroborate
mid 16th century (in the sense ‘make physically stronger’): from Latin corroborat- ‘strengthened’, from the verb corroborare, from cor- ‘together’ + roborare, from robur ‘strength’.
wiktionary
From Latin corrōborātus(“strengthened”), perfect passive participle of corrōborō(“I support, corroborate”), from com-(“together”) + rōborō(“I strengthen”), from rōbur(“strength”).
etymonline
corroborate (v.)
1520s, "to give (legal) confirmation to," from Latin corroboratus, past participle of corroborare "to strengthen, invigorate," from assimilated form of com "with, together," here perhaps "thoroughly" (see com-) + roborare "to make strong," from robur, robus "strength," (see robust).
Meaning "to strengthen by evidence, to confirm" is from 1706. Sometimes 16c.-18c. in its literal Latin sense "make strong or add strength to," especially of medicines. Related: Corroborated; corroborating; corroborative.