According to this site
Transitive Property of Equality.
If one value (a) is equal to another value (b), which is equal to another value (c), then the first value (a) is equal to the third value ...
I have never heard of the term before.
Example: "larger than" is a transitive property.
If A is larger than B and B is larger than C then A is larger than C.
Example of non-transitive property: "mother of"
If A is mother of B and B is mother of C then A is not mother of C.