Here are some commonly used ballet and dance terms. If I have used a word in a post that you think I should define here, please let me know! American Ballet Theatre also has a wonderful online ballet dictionary, which can be found here.
Pas de deux: A dance for two. A classical pas de deux follows a standard format of a supported adagio (slow) section, with the man and woman dancing togethter; then variations for each of them; then a coda (fast-paced finale). However, a pas de deux can be any dance specifically for two people–classical or contemporary, man/woman, man/man, or woman/woman.
Variation: A solo dance.