Meaning of EXTENSION in English

[ex.ten.sion] n [ME, fr. MF or LL; MF, fr. LL extension-, extensio, fr. L extendere] (15c) 1 a: the action of extending: state of being extended b: an enlargement in scope or operation "tools are ~s of human hands"

2. a: the total range over which something extends: compass b: denotation

4. 3 a: the stretching of a fractured or dislocated limb so as to restore it to its natural position b: an unbending movement around a joint in a limb (as the knee or elbow) that increases the angle between the bones of the limb at the joint--compare flexion 4a

4: a property whereby something occupies space

5: an increase in length of time; specif: an increase in time allowed under agreement or concession "was granted an ~"

6: a program that geographically extends the educational resources of an institution by special arrangements (as correspondence courses) to persons otherwise unable to take advantage of such resources

7. a: a part constituting an addition b: a section or line segment forming an additional length c: an extra telephone connected to the principal line 8: a mathematical set (as a field or group) that includes a given and similar set as a subset

Merriam-Webster English vocab.      Английский словарь Merriam Webster.