Hello! It has been a while. So it's time to get back to talking about terminology.
What, really, is a "cha-cha" step? I don't know that I have the entire, complete, perfect answer, but here is what I have learned from many teachers over many years: It is a composite of two other basic steps.
In essence, a "cha-cha" step is a Mambo/Chasse' and fills 4 beats. Most commonly you will have two to complete an 8-count. The Chasse' step has already been covered, so I will not be covering it again.
Mambo Step. Often, it is cued as "Rock-Recover."
This step moves all directions: forward, side, back, diagonal. In Latin styled dances it includes hip action. So you place one foot, rocking your weight onto it, and on the second beat, rock your weight back to the original foot.
Cha-Cha: Forward and Back - Beats 1 and 2 are the mambo, beats 3 & 4 are the chasse'
1. Step forward on R foot
2. Recover weight back to left
3&4. Chasse' back (RLR)
5. Step (or rock) back on the R foot
6. Recover weight to the left
7&8. Chasse forward (RLR)
When you do this step to the side, the chasse' step is either done with one foot crossed over the other, or you turn your body to chasse' in a forward motion.
One interesting aspect of the Cha-cha step is how it is defined in different dance disciplines. In common use, it is "Rock-Recover-Chasse' but when it is used in professional dance disciplines, it is "Chasse'-Rock-Recover."
So whenever you encounter this fun step, watch to see which way it is being used, and enjoy!
(Oh, and there is more to the "mambo step" story - that's for next time! Happy Dancing!)