Here's how it works:
* Academic:
* Academy: A place of learning.
* Academic: Relating to or characteristic of an academy or learning.
* Examples: "She is an academic in the field of history." "This is an academic paper."
* Volcanic:
* Volcano: A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are erupted from the earth's crust.
* Volcanic: Relating to or characteristic of a volcano.
* Examples: "The island has a volcanic origin." "This rock is of volcanic material."
In both cases, "-ic" transforms the base word into an adjective that describes something connected to or resembling the original noun.