The notions of metric tangency and metric jet are generalizations of notions from differential calculus such as tangent vectors and jet spaces to the setting of arbitrary metric spaces.
Let and be metric spaces, two maps, and .
We say that and are tangent at if and the function defined by
is continuous at .
Now let be another point.
The set of jets from to is the quotient set of the set of maps which are locally Lipschitz? at and satisfy by the equivalence relation of tangency at .