>>12183728A word that has many different meanings.
Set theory: the cardinalities/ordinalities of sets which have more than any natural number of elements. (There are many different numbers called infinity here - an infinite number of them, to be exact).
Real/complex analysis: not so much a number as a notational shortcut used to describe limits where (the absolute value of) a number becomes arbitrarily large.
Projective geometry: see
>>12183793.
As for
>>12183782 and
>>12184094, we can think about them as the limits of the sequences (9, 99, 999, ...) and (1, 11, 11, ...), etc, so they're infinite in the analysis sense. However, if we insist on interpreting them as numbers in their own right, they're part of the 10-adic numbers. Their values are -1 and -1/9, respectively, not infinite.
