Gimlet

A gimlet, according to its original meaning, is a kind of tool for boring holes. It was defined in Gwilt's Architecture (1859) as "a piece of steel of a semi-cylindrical form, hollow on one side, having a cross handle at one end and a worm or screw at the other".

The term is also used figuratively to describe something as sharp or piercing, and also to describe the twisting, boring motion of using a gimlet. The term gimlet-eyed can mean sharp-eyed or squint-eyed.

Gimlet Coctail

The Gimlet is a cocktail typically made of

2 ounces gin
2 ounces bottled sweetened lime juice (such as Rose's)
1 teaspoon sugar

Stir well with ice. Strain into pre-chilled cocktail glass. Sugar-frost rim of glass.

A 1928 description of the drink was: "gin, a spot of lime, and soda" (D. B. Wesson, I'll never be Cured III). A 1953 description was: "a real gimlet is half gin and half Rose's Lime Juice and nothing else" (R. Chandler, Long Good-Bye).

For the Vodka Gimlet, replace gin with vodka. As of the 1990s, maybe earlier, bartenders often answer requests for the gimlet with a vodka gimlet. They may also serve the gimlet on the rocks.

Surgeon Rear-Admiral Sir Thomas Desmond Gimlette (1857-1943) served in the Royal Navy during the time period when cocktails started to become popular. A naval medical officer would certainly have access to gin and lime juice. However, neither his obituary notice in The Times of October 6, 1943, nor his entry in Who Was Who, 1941-1950, mentions any inventiveness with regard to cocktails.

References

"gimlet", Oxford English Dictionary, 2nd ed. (1989).