extension

noun ! Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about extension at Wordnik → Where our words come from →

1. The act of extending; a stretching out; enlargement in length, breadth, or time; an increase.

   Next month the house is undergoing an extension.

2. The state of being extended.
3. That property of a body by which it occupies a portion of space (or time, e.g. "spatiotemporal extension").