Sneaking vs Pernicious - What's the difference?

As a verb sneaking

is present participle of lang=en.

is the act of one who sneaks.

causing much harm in a subtle way.

(head)

(en noun)

The act of one who sneaks.

* 1915 , Charmian London, The Log of the Snark (page 108)

Then there was much mirth and banter over the swift sneakings for home of certain men carrying large portions of puarka .

(en adjective)

Causing much harm in a subtle way.

* 1911 , ,

Puritanism no longer employs the thumbscrew and lash; but it still has a most pernicious hold on the minds and feelings of the American people.

Causing death or injury; deadly.

* (l)

* perniciousness * perniciously