A gratuity is a large gift of money that is given to someone when they leave their job, especially when they leave the armed forces. He is taking a gratuity from the Navy
Also known as co-op or honorarium Money given to respondents of a study Usually given when the interview is longer than a few minutes, respondents are asked to travel or take part in more than one phase of research, or respondents are business professionals
an award (as for meritorious service) given without claim or obligation a relatively small amount of money given for services rendered (as by a waiter)