The term 'social media metric' refers to the measurement of the success of a social media campaign. One of the most common metrics used is 'likes', which is a five-letter word. Likes are a way for users to show their approval of a post or page, and can be used to measure the engagement of a post or page. This metric is often used to gauge the success of a social media campaign, as it provides an indication of how many people have seen and interacted with the content.