Without reward or consideration. 2. When a bailee undertakes to perform some act or work gratis, he is answerable for his gross negligence, if any loss should be sustained in consequence of it; but a distinction exists between non-feasance and misfeasance; between a total omission to do an act which one gratuitously promises to do, and a culpable negligence in the execution of it; in the latter case he is responsible, while in the former he would not, in general, be bound to perform his contract. Freely; gratuitously; without reward or consideration.
GRATIS
TheLaw.com Law Dictionary & Black's Law Dictionary 2nd Ed.