A 1928 description of the drink was: “gin, a spot of lime, and soda”. The description in the 1953 Raymond Chandler novel The Long Goodbye stated that “a real gimlet is half gin and half Rose’s lime juice and nothing else”.
The word “gimlet” used in this sense is first used in 1928. It’s believed that this is named after a tool for drilling small holes, a common metaphor to describe something as sharp or piercing. The cocktail was likely named after this because of it’s strength in both potency and flavour.