There are, however, two words/terms that I still find very challenging to define properly and to differentiate: movement and motion. In Norwegian we only have one word (bevegelse) for describing movement/motion, which makes everything much simpler. But when writing in English, which word should be used? and what is the difference?

It only adds to the confusion that Wiktionary defines movement as “physical motion between points in space”. And Wikipedia has a page on motion (in physics), while none of the many movement pages are related to body movement.

During the last years I have asked many native English speakers about the difference between motion and movement, but have not received any good explanations yet. Many of them think they are slightly different, although this is usually based on their feeling rather than on a proper explanation of the difference. Some native speakers think the two words are the same and can be used interchangeably.

I have also asked researchers working on various types of movement-oriented disciplines about their use of the words, and they often tend to stick to one or the other. From these discussions I have come to think that people working in biomechanics and physics prefer motion, while people  working in physiotherapy, dance and music prefer movement. That motion is a more scientific term is is also suggested here. From this we could assume that motion is related to measurable displacement of objects, which the term motion capture attest to, while movement refers to the qualities or meaning of the displacement.

The above assumptions are, however, only my assumptions. So I thought it would be interesting to see if I could get some more empirical data on the topic. So I decided to use the powers of Google to quantify the differences. Here are some figures from google and google scholar:

So, clearly, movement seems to be used much more frequently than motion in general language, and also in the scientific literature. However, body movement and body motion are used almost the same amount of times in scientific papers.

But what if we search for the use of the two terms in different fields? Then we get these numbers:

Again, we see that movement is generally used more than motion, even in physics and mechanics. I am quite surprised that music+motion is used so frequently, particularly since movement has a double meaning in music (i.e. parts of a piece).

What to conclude from all of this? I still do not know what the difference between movement and motion is, and the numbers show that movement is used more than motion also in the disciplines that I thought used motion almost exclusively. Still I like the idea that motion is used to describe physical properties, while movement is used to describe the qualities of motion. So I will stick to that for a while myself.

What do you think? Any comments or suggestions are highly welcome!