A G-string is a narrow band of cloth that is worn between a person's legs to cover their sexual organs, and that is held up by a narrow string round the waist.
G-string in British English
noun
1.
a piece of cloth attached to a narrow waistband covering the pubic area, worn esp by strippers
2.
a strip of cloth attached to the front and back of a waistband and covering the loins
3. music
a string tuned to G, such as the lowest string of a violin
G-string in American English
(ˈdʒiˌstrɪŋ)
US
noun
1.
a narrow loincloth
2.
a similar cloth or band, as worn by striptease dancers