noun
plural -sions
the act of extending something: such as
the act of making something longer or greater [noncount]
the act of straightening or stretching something (such as an arm or a leg) [count]
[count] :extra time allowed for doing something
[count] :something (such as an interest or activity) that develops from something else - + of
The phrase by extension is used to say that what follows comes from or is connected with something that has already been mentioned.
[count] a part that is added on to something to make it larger or longer
extension cord
[count] :an extra telephone that is connected to the main line