Definition of "instrumental role" []

• The semantic role of the entity (usually inanimate) that the agent uses to perform an action or start a process (noun)

WordNet. Princeton University. 2010.

• "The design of the Harrisburg parks tends to the naturalistic, for although Manning played an instrumental role in founding the American Civic Association and the American Society of Landscape Architects, both bulwarks of the City Beautiful movement, he was not sympathetic to Beaux Arts–style planning and much preferred the picturesque approach of his mentor, Olmsted."
• "At the Oklahoma Medical Research Foundation, John Harley has played an instrumental role in identifying a pair of genes in humans that may be responsible for genetic susceptibility to lupus."