Definition of "extension"
noun
countable and uncountable, plural extensions
The state of being extended
Quotations
For station is properly no rest, but one kind of motion, relating unto that which physicians (from Galen) do name extensive or tonical; that is, an extension of the muscles and organs of motion, maintaining the body at length, or in its proper figure.
1650, Thomas Browne, Pseudodoxia Epidemica: […], 2nd edition, London: […] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […]