- Adjective. being a distinguishing feature of a person or thing.
- Noun. a distinguishable feature of a person or thing.
- Noun. (mathematics) the integer part of a logarithm.
- Noun. (nautical) the distinguishing features of a navigational light on a lighthouse etc by which it can be identified (colour, pattern of flashes etc).
- Noun. (algebra, field theory) The minimum number of times that the unit of a field must be added unto itself in order to yield that field's zero, or, if that minimum natural number does not exist, then (the integer) zero.