Fimbriae, also known as pili, are thin, hair-like structures found on the surface of certain bacteria. These structures serve various functions, including helping bacteria attach to surfaces, aiding in DNA transfer between bacteria during conjugation, and aiding in bacterial motility. There are various synonyms for the word fimbriae, including pilus, flagellum, filament, appendage, frill, and tendril. These terms can be used interchangeably to refer to the same structures found on the surface of bacteria. Understanding the synonyms for fimbriae is essential for appropriate description and identification of bacterial structures and functions.