If you do something nice without being paid, you do it “gratis.” Technically, such a deed can also be “gratuitous”; but if you do or say something obnoxious and uncalled for, it’s always “gratuitous,” not “gratis.”
gratis /gratuitous
If you do something nice without being paid, you do it “gratis.” Technically, such a deed can also be “gratuitous”; but if you do or say something obnoxious and uncalled for, it’s always “gratuitous,” not “gratis.”