Glossary!

Quatrième ["fourth"]: Fourth position. (See feet, positions of and arms, positions of.)
Quatrième, à la ["in the fourth"]: À la quatrième devant is with the working leg stretched out to the front; à la quatrième derrière is with the working leg stretched to the back.
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Relever ["to rise"]: One of Noverre's seven movements (see movements).
Relevé ["raised"]: A movement in which the heels are raised off the floor. The rise may be smooth or aided by a slight spring, depending on the school. A dancer in such a position is said to be "in relevé."
Retiré ["withdrawn"]: A position in which the working foot is drawn up to the knee of the supporting leg. Also frequently (and incorrectly) called passé.
Rond de jambe ["circular movement of the leg"]: A movement in which the working leg is made to describe a letter D about the supporting leg. May be done with the working foot on the floor or in the air. In a rond de jambe en dehors ("outward") on the floor, the working leg moves from first (or fifth) position to pointe tendu forward, makes a half circle to pointe tendu in back, and then returns to first, if the rond de jambe is to be repeated, and otherwise to first or fifth. A wonderful exercise for turnout. In a rond de jambe en dedans ("inward"), the direction of movement is reversed. In a demi rond de jambe, the working leg goes only half-way around, stopping in second position. A grand rond de jambe, is executed with the supporting leg in plié. A rond de jambe en l'air ("in the air") is done with the working leg raised off the floor, frequently at an angle of 90 degrees (parallel to the floor).
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Sauter ["to leap"]: One of Noverre's seven movements (see movements).
Seconde, à la ["in second"]: In second position, i.e., to the side. (See feet, positions of and arms, positions of.)
Sissonne [Named for its inventor]: A type of jump that has several forms, among them: sissonne simple, sissonne ouverte, sissonne fermée, sissonne fondue, and others. Not to be confused with ciseaux.
{ In sissonne simple, the most elementary form, the movement begins in 5th position. Jump straight up, with the legs together and the feet pointed. Land on one foot in demi-plié, with the other foot sur le cou-de-pied either in front or back (corresponding to whether the foot sur le cou-de-pied began in front or back--it does not change). }
Soubresaut ["sudden leap"]: A jump from both feet to both feet. Beginning in 5th croisé, the feet push off the floor so that the body flies forward with feet pointed and legs together. Before the jump, the body inclines forward, and then during the jump bends forcefully back, so that the legs remain at the back. The movement ends in 5th croisé. The arms are free and depend only on the design of what is being sought after; when studying, they usually begin in preparatory, come up to first during the jump, and end in preparatory again.
Sous-sus ["under-over"] (or sus-sous ["over-under"]): A relevé in a tight fifth position with one foot almost on top of the other.
Soutenu ["sustained"]: (a) Performed smoothly and slowly. (b) Also used to indicate a smooth détourné. For (a), can be: where from 5th position, the working leg is taken out to the front, 2nd position, or to the back, while the supporting leg is lowers to demi-plié. Then the supporting leg rises to demi or full pointe while the working leg is drawn into it, ending in a tight sus-sous position.
Spotting: A technique for for keeping oriented and avoiding dizziness during turns. Pick a spot (some conspicuous object); keep looking at it as you turn until you can't any longer; then quickly turn your head so you are looking at it again.
Sur le cou-de-pied: See cou-de-pied, sur le.
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Temps: Literally, "time," but perhaps "moment" would be better. A movement that forms part of a step. Grant says a part in which there is no transfer of weight, which raises some interesting questions about temps lié.
Temps levé ["raised movement"]: Temps levé is the very simplest jump from one foot onto the same foot with the other foot raised.
Temps lié ["joined movement"]: This is a term for a whole series of conventionally connected movements executed in the center of the room, often during an adagio. However, it is also the term for an independent form of a step. In the basic form of the temps lié, stand in 5th position croiseé, arms in preparatory position. The working leg is drawn, without taking the toe off the floor, into croisé devant, while the supporting leg bends into demi-plié; simultaneously, the arms are raised into 1st position with the head slightly inclining towards the shoulder corresponding to the supporting leg. Then, the weight is transferred through demi-plié to croisé derrière onto what was the working leg. Here, both legs are completely stretched with the now working leg stretched toe to the floor in back. At the moment of weight transfer, the arm that corresponds to the now working leg is raised overhead, while the other arm opens sideward; the head turns towards the sideward arm. Finally, the working leg closes in 5th back; arms may remain or stay.
Tendu ["stretched"]: See: battement tendu and pointe tendu.
Terre-à-terre ["ground to ground"]: Used to describe steps in which the dancer's feet do not leave the floor. Antonym: movements).
Travesti, en ["in disguise"]: Of a female dancer: dancing a male role in a man's costume; of a male dancer: dancing a female role in a woman's costume.
Turnout: The balletic stance in which the legs are rotated outward so that the legs (and feet) point in opposite directions. A dancer adopting this position is said to be "turned out." Usage varies, but most people seem to measure the degree of turnout by the angle between the foot and the mid-saggital plane of the body. The ideal, with both feet in a straight line, is thus 90 degrees of turnout. Turnout must begin at the hip. Forcing the feet and letting everything else follow puts severe strain on the joints, especially the knees, and defeats the purpose of turnout, which is to rotate the thigh bone to permit greater extension, especially to the side.
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Sources
1. Parsons, Tom. "100 (more or less) Common Ballet Terms Defined". http://www.home2.planetinternet.be/tor-4084/links.htm released: Aug. 19, 1999. (letters M-Z)
2. Vaganova, Agrippina (as translated by Chujoy, Anatole). "Basic Principles of Classical Ballet". Dover Publications, Inc. New York, 1969. (letters A-H)
3. Charlotte and her experience as a dancer.