In common usage, a dimension is a parameter or measurement required to define the characteristics of an object— i.e. length , width , and height or size and shape . 3D is the terminology that we as the dimensions have given earth according to the structure of how earth is made up according to its measurement.
When you are experiencing earth you are in fact in a 3D reality. Earth is 3 dimensional because of its structure. It consists of structures that are as the name describes, is able to be seen and experienced in all 3 dimensions. Your physical world therefore has been designed and structured according to these three parameters. 3D contains all 3 dimensions and is able to at any moment contain an object measured according to one dimension, but our perception and experience of this world is three dimensional.
Within 3D as earth – consist the movement of space and time – where everything literally moves extensively slowly compared to dimensional movement with quantum time. 3D movement is like a tortoise whilst dimensions would be a jet – yes – the extent to the slow movement within 3D.