extension

Noun
  1. The act of stretching or lengthening something. Noun
    She reached the full extension of her arm.
  2. A lengthened part that is added to something. Noun
    The house has a new extension.
  3. An increase in the period of time allowed for something. Noun
    The deadline was given a two-week extension.
synonyms: expansion, lengthening, stretch, prolongation