Tempo

A musical term referring to the speed of either the music or the movement.

Timochenko

A side flexion performed in standing side splits - named after the soviet gymnast, Alexandra Timochenko.
(Picture from rsg.net)

Toebreaker (downwards)

The gymnast (from a standing position on toes) drops into a kneeling position. During the drop to the knees, the back arches and head drops backwards.

Toebreaker (upwards)

Similar to a downwards toebreaker except in reverse (from knees to standing)

Toe shoe

half shoe made from leather and synthetic material with elastic around the ankle that makes it easier to perform movements such as pivots.

Toss

A small throw from one hand to the other.

Tour Jete

A jump with a half turn in which weight is transfered from one foot to the other.

Trio

A multiples routine performed by three gymnasts with either the same apparatus, or 2 the same and one different (but not all different).
(Picture from Nikki Johnson)

Tuck

A position in which the knees are bent and close to the chest.

Turn

similar to a pivot, but done with both feet on the ground (rather than on 1 foot)

Turnout

The way the feet and legs should be turned out from the hip joints to give the necessary freedom of movement to perform the steps of classical ballet.