By rigorous statistical standards, the expression false negative rate is a misnomer because the concept of" rate" is associated with the rapidity of change of phenomena per unit of time or other variable (eg, temperature). Uncertainty about the term false negative rate resulted in the introduction of similar but equally dubious expressions, including false negative fraction and miss rate. The statistically correct term in the practice of cytopathology is false negative proportion because we have here a fraction in which the numerator (number of false negative cases) is a part of the denominator (number of true positive cases plus number of false negative cases). This is the classic definition of the term proportion.