The name Lindsay is a girl's name of English origin meaning "marshlands of Lincolnshire". Lindsay and is often added to lists like Unisex Names for Girls and discussed in our forums with posts like "Sibsets You Know".
From the experts:
In the early eighties, Lindsay, in tandem with Courtney, approached the Top 10. Lindsey is one of the few truly unisex names (rather than being a name that has changed genders). Over time the ey ending was usually reserved for women and the ay ending reserved for men. This tradition continues in the 2014 Top 1000 rankings, with Lindsey retaining a considerable lead over Lindsay among girls in the USA. In the UK, however, Lindsey makes no appearance in the Top 3000 at all, and Lindsay was only given to 6 girls in 2013, ranking at Number 2443.