ENDEC is a term often used in radio communication, particularly in Morse code. It is a signal that indicates the end of a transmission. However, if you're looking for synonyms to use in everyday conversation, there are plenty of options available. Some of the most commonly used include conclusion, end, culmination, termination, finale, wrap-up, and completion. For a more formal tone, you could use terms such as cessation, denouement, or epilogue. No matter which synonym you choose, it's important to indicate the ending of an activity, conversation, or communication clearly to avoid any confusion or misunderstanding.