to support (e.g. a claim or an opinion) with evidence or authority
corroboration /-ʹraysh(ə)n/ noun
corroborative /-tiv/ adj
corroborator noun
corroboratory /-ət(ə)ri/ adj
[Latin corroboratus, past part. of corroborare to give added strength, from cor- + robor-, robur strength]