If you're dissatisfied, you're not happy — you're annoyed and disgruntled. You probably don't enjoy eating out with your parents if they're always dissatisfied with the food they order.
You might be dissatisfied with the final episode of your favorite TV show, or dissatisfied with your grades n German last semester. In either case, you're not pleased. A slightly different way to be dissatisfied is to be unconvinced: "She was dissatisfied with the answer he gave when she asked when he planned to pay back the money he owed her." Dissatisfied combines dis-, "not," and satisfied, from a Latin root, satisfacere, "do enough."