Institute of Management Accountants (IMA) definition. Analyzing the definition of key terms often provides more insight about concepts. Institute of Management Accountants (IMA) can be defined as – A professional association of management accountants. Many accountants aspire to become certified as a CPA, Certified Public Accountant providing assurance of the knowledge of an individual related to accounting concepts. The Institute of Management Accountants (IMA) provides a certification process specific for managerial accounting topics, a Certified Managerial Accountant (CMA). The Certified Managerial Accountant CMA provides assurance about a set of skills specific to managerial accounting.