The definitions of "slow learners" and "borderline intellectual functioning (BIF)" have not reached a consensus and have continually evolved in terminology. The criteria for diagnosing BIF include the Full-Scale Intelligence Quotient, adaptive functioning, and onset of symptoms from the developmental period; however, specific standards have not been provided. Until the Diagnostic and Statistical Manual of Mental Disorders-IV, a range for the Full-Scale Intelligence Quotient was provided, but due to its limitations in reflecting the actual functioning of individuals with BIF, this criterion was removed from the Diagnostic and Statistical Manual of Mental Disorders-5. The absence of specific diagnostic criteria complicates the identification of individuals with BIF, highlighting the need for a more precise classification and definition.