infinity

The largest value that can be represented in a particular type of variable (register, memory location, data type, whatever).
minus infinity: The smallest such value, not necessarily or even usually the simple negation of plus infinity. In N-bit twos-complement arithmetic, infinity is 2^N-1 - 1 but minus infinity is - (2^N-1), not -(2^N-1 - 1). Note also that this is different from time T equals minus infinity, which is closer to a mathematician's usage of infinity.