earnest or emphatic in dwelling upon, maintaining, or demanding something; persistent; pertinacious.
Is insistent a noun or adjective?
INSISTENT (adjective) definition and synonyms | Macmillan Dictionary.
What is an example of insistent?
The definition of insistent is demanding or persistent. An example of an insistent person is someone who keeps giving support for a lie, no matter how many times he is questioned or proved wrong.