- Term used to describe the ability of a dancer to raise and hold her extended leg en l'air. A dancer is said to have a good extension if, when doing a développé à la seconde, she is able to hold and sustain the raised leg above shoulder level.
- The ability to raise the working leg high in the air. Good extension comes from a combination of inborn flexibility and training. Source: Vance's Fantastic - BALLET DICTIONARY
How extended a range of frequencies the device can reproduce accurately. Bass extension refers to how low a frequency tone will the system reproduce, high-frequency extension refers to how high in frequency will the system play. Source: http://www.owenscorning.com/around/sound/glossary.asp