From Latin vindicātus, perfect passive participle of vindicō (“lay legal claim to something; set free; protect, enge, punish"), from vim, accusative singular of vÄ«s (“force, power"), + dÄ«cō (“say; declare, state").
From Wiktionary
Latin vindicāre vindicāt- from vindex vindic- surety, enger deik- in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition