The colon is the symbol ":". It is used in a number of different ways in mathematics.
1. To denote ratio or odds, as in 2:1 (voiced "two to one").
2. To mean such that in constructions such as 
(voiced "the set of numbers 
such that 
).
3. To give a name to a map, e.g., 
(which is equivalent to the function
notation 
).
4. As a part of the symbol 
sometimes used to mean "
is defined as 
."
5. To delineate the three elements of trilinear coordinates, i.e., 
.
6. To indicate an extension field degree of an extension field 
, denoted ![[K:F]](/images/equations/Colon/Inline11.svg)
.
7. To denote colon product of two dyads.
