Can a dielectic MATERIAL IS A INSULATOR?

[SAINATHAN]

When a dielectric material insert between two plate capacitors the conductivity may increase.
Normally we talk that a dielectric is insulator?but how can it increases
conductivity?

 

[Apteronotus]

Do you mean capacitance will increase?

Here's a link you may find useful.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/dielec.html#c2