Fulfillment is a feeling of happiness and satisfaction. It's also the completion of something, like the fulfillment of a promise.
This word has two related meanings. In terms of emotions, fulfillment is a happy, contented feeling. Many people feel fulfillment from being a parent, having a great job, or graduating from school. People often feel fulfillment when something is completed, whether it's a goal or a dream or repair work that you've been waiting on. Which leads to the other meaning of fulfillment — the act of finishing or doing something that was promised.