Origin: Latin suffix -al
Congressional has 3 different meanings across 1 category:
Of or pertaining to a congress.
"The congressional committee held hearings to investigate the proposed legislation."
Of or pertaining to the United States Congress.
In plain English: Congressional means anything related to the members of Congress who make laws for the country.
"The congressional committee held hearings on the new budget proposal."
The word comes from combining congression with the suffix -al. It entered English to describe anything related to a congressional body or its members.