What does rhythm mean when it comes to a periodic function like sine or cosine? I found this online click

I don't know what rhythm means.  I can't really find where it means anywhere.  Maybe I'm not a good searcher but I really really try to search it out.  I know the period is the length of one cycle.  I know the amplitude is the halfway distance between the max and min of a sine or cosine function.  I know the frequency is the number of cycles completed in a unit interval.  

What does rhythm mean here?
I think it means whether it starts at the top and then goes down or starts at the bottom and then goes up. So, for the standard sine curve I would say the rhythm is "middle, top, middle, bottom, middle" Or "Up, down, up, down". I wasn't sure about it at first, but I think it will help them once they graph their starting, ending, max and min points. Then, they know for the sine function that they will go "middle, top, middle, bottom, middle". Or, we could use more math terms and say, "zero, max, zero, min, zero" Then for cosine, we could say "max, zero, min, zero, max." This would help later when putting it all together because they could take 1/4 of a period and mark each point following that rhythm. I actually think I like this way of thinking about it.
I think it means whether it starts at the top and then goes down or starts at the bottom and then goes up. So, for the standard sine curve I would say the rhythm is "middle, top, middle, bottom, middle" Or "Up, down, up, down". I wasn't sure about it at first, but I think it will help them once they graph their starting, ending, max and min points. Then, they know for the sine function that they will go "middle, top, middle, bottom, middle". Or, we could use more math terms and say, "zero, max, zero, min, zero" Then for cosine, we could say "max, zero, min, zero, max." This would help later when putting it all together because they could take 1/4 of a period and mark each point following that rhythm. I actually think I like this way of thinking about it.