The Probert Encyclopaedia of General Information

EXTENSION

In logic, extension is the extent of the application of a general term, that is, the objects collectively which are included under it; thus, the word figure is more extensive than triangle, circle, parallelogram, etc; European more extensive than French, Frenchman, German, etc. Matter and mind are the most extensive terms of which any definite conception can be formed. Extension is contrasted with comprehension or intension.
Research Extension