Carrisa is correct, when two roads meet, we call the point at which they meet, an intersection, and "intersection" is the word commonly used in North America.
The noun "intersection" is the result of two roads that "intersect each other".
The verb "intersect" is made up of "inter" (between) and "sect" (to cut).
So, when two or more roads cut across each other, the result is an intersection.
For example: 2 roads that meet and intersect each other could look like "+" or "x"
These roads definitely "cut across" each other.
However, another defintion of intersection is related to mathematics... meaning "where two points meet".
So, in your question:
- in the "T" example there are 2 roads, and the single intersection is the point at which they meet (even though the roads don't "cut across" each other).
- in the "Y" example there are 3 roads, but only one insection from the point of view of a driver (even though the roads don't "cut across" each other).
Tim has given an excellent explanation of the less-often used term "crossroads".