Dyslexia is a specific learning disability that is neurobiological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.
International Dyslexia Association definition and the definition adopted in Tennessee HB 1735 / SB 2002

This definition of dyslexia is adopted by the state of Tennessee. It explicitly defines dyslexia as a specific learning disability. Any child identified with a specific learning disability in basic reading or a specific learning disability in reading fluency has been identified as having dyslexia under current federal and state laws.

"Characteristics of dyslexia" is a more inclusive term that does not require that a student be identified with a specific learning disability. The term is adopted in Tennessee HB 2616 / SB 2635. It was adopted to ensure that students who struggle with word reading skills in any grade (K - 12) receive appropriate direct systematic instruction to teach them to read words accurately and / or fluently in support of comprehending written language.

Both terms "dyslexia" and "characteristics of dyslexia" apply to public schools in Tennessee in accordance with Tennessee HB 1735 / SB 2002 and Tennessee HB 2616 / SB 2635.