which way is width
If you were to look directly down on the object, you would just see a rectangle. The longest side is the length and the shorter is the width. The height is how high the ds is from where it sits on the table to its top. They are but should not be ambiguous. A cylinder that is 12 TALL and 6 across (diameter) when it is standing on end will be 12 LONG and 6 tall laying on its side. Most of the time the context makes it clear which is which, however I tend to think that 'length' refers to horizontal measure and height' refers to vertical measure.