characteristic

A distinguishing feature of a person or thing.

(mathematics) The integer part of a logarithm.

(nautical) The distinguishing features of a navigational light on a lighthouse etc by which it can be identified (colour, pattern of flashes etc.).

(algebra, field theory, ring theory) For a given field or ring, a natural number that is either the smallest positive number n such that n instances of the multiplicative identity (1) summed together yield the additive identity (0) or, if no such number exists, the number 0.