What's the high school definition of 2 perpendicular lines in 3D space in the UK and the US?

Question

In my country, 2 lines in 3D space are said to be perpendicular if the angle between them is 90 degrees, and the angle between 2 lines in space are said to be the (either right or acute) angle of 2 coplanar lines each of which is parallel to 1 of the original lines. For example, if line d and line b are coplanar, the angle between them is very obviously the right or acute angle at their point of intersection, and if that angle is right, line d is perpendicular to line b. However, if line d and line b are not coplanar, they can still be perpendicular if there exists a line that's parallel to line d but also coplanar and perpendicular to line b. I don't know about the terminology, definitions or conventions in terms of perpendicularity in the UK or the US. So I'm curious whether 2 lines have to be coplanar (have a point of intersection) to be perpendicular in 3D space or not.