Definitions for "Unique Visitor"
A unique visitor is someone who has not been to the site before or within the past 12 - 48 hours.
Website traffic measurement where each person's individual IP address visiting a particular website is counted only once, regardless of how many times they visit that particular website in a given day.
The number of visitors who access a Web site within a given time period (usually 24 hours) from a single IP address. If you visit the same Web site three times within a 24 hour period, your visits only count as one unique visit for that day.
Keywords:  audience, see
see unique audience.
A session of activity by one user, identified by a unique IP address or a cookie
Keywords:  thing, hard, come, days
a hard thing to come by these days