Learn the English definition and meaning of Thong with examples, pronunciation, and translations to enhance your vocabulary. thong (plural thongs) In Australia, "thongs" tends to refer to footwear. In the United Kingdom and the United States, "thongs" tends to refer to undergarments. A narrow strip of material, typically leather, used to fasten, bind, or secure objects. The thong is a garment generally used as either underwear or in some countries, as a swimsuit. It may also be worn for traditional ceremonies or competitions. Viewed from the front, the thong typically resembles a bikini bottom, while at the back the material is reduced to a minimum. Thong definition: a strip of material, especially of leather or hide, used to fasten or secure something.. See examples of THONG used in a sentence.