A fifer is a marching-band musician who plays the fife, a small, high-pitched flute-like instrument. Fifer is a five-letter word that is often used to describe a marching-band musician who plays the fife. The fife is a small, high-pitched flute-like instrument that has been used in marching bands since the 16th century. It is usually made of wood and has six finger holes and one thumb hole. Fifer is an important part of a marching band, as they provide the melody and rhythm for the band.