Main Entry: bi•ki•ni
Pronunciation: \bə-kē-nē\
Function: noun
Etymology: French, from Bikini, atoll of the Marshall Islands
Date: 1947
1 a: a woman's scanty two-piece bathing suit
   b: a man's brief swimsuit
2: a man's or woman's low-cut briefs
— bi•ki•nied also bi•ki•ni'd \-nēd\ adjective
 

Main Entry: string bikini
Function: noun
Date: 1974
: a scanty bikini with string-like straps
 

Main Entry: thong
Pronunciation: \thoŋ\
Function: noun
Etymology: Middle English, from Old English thwong; akin to Old Norse thvengr thong
Date: before 12th century
1 : a strip, especially of leather or hide
2 : a sandal held on the foot by a thong fitting between the toes and connected
     to a strap across the top or around the sides of the foot
3 : swimwear or underwear consisting of a narrow strip of material that passes between the thighs and connects with a waistband
— thonged \ˈthȯŋd\ adjective
 

as per Merriam-Webster