gratuitous (adj.) Look up gratuitous at Dictionary.com
1650s, "freely bestowed," from Latin gratuitus "done without pay, spontaneous, voluntary," from gratus "pleasing, agreeable," from gratia "favor" (from suffixed form of PIE root *gwere- (2) "to favor"). Earlier was gratuital (1590s). Sense of "uncalled for, done without good reason" is first recorded 1690s.