In mathematics, "infinity" is often used in contexts where it is treated as if it were a number (i.e., it counts or measures things: "an infinite number of terms") but it is a different type of "number" than the real numbers. Infinity is related to...

Interferon, cytokine produced by the cells of the immune systems

Informatics, the science of information and the practice of information processing

Intermediate-Range Nuclear Forces Treaty, also known as the INF Treaty

Infimum, for which the mathematical abbreviation is inf

Irish National Federation

International Naturist Federation

INF file, a file extension (information file) used by software and hardware driver installation routines