What is Dyslexia?

Quick Facts about Dyslexia

  • Defined as extreme difficulty reading caused by a hereditary, brain based, phonologic disability
  • Symptoms include poor reading, spelling, fluency as well as difficulty with short term memory and auditory discrimination
  • Dyslexics struggle to quickly and accurately identify and manipulate the basic sounds of language (phonemes)
  • It is not a disease, a gift or something that will be grown out of
  • Often associated with dysgraphia, dyscalculia and dyspraxia and ADHD
  • Very treatable through effective reading programs, assistive technology and classroom accommodations 
  • For all the basics on dyslexia in one handy reference source, check out our U.S. Parent Guide.

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Glossary of Dyslexia Related Terms

Definition of Dyslexia


Definition of dyslexia:

Extreme difficulty reading caused by a hereditary, brain based, phonologic disability



Dyslexia is composed of two Greek root words:

Dys (Difficult)
Lexia (words)

Very simply, it's difficulty with words. Even the Greeks knew it wasn't about reading backwards.

What is dyslexia? Probably not what you think

Typically people think that dyslexia has something to do with seeing letters or words written backward, upside down, moving around or off the page. In fact most dyslexics don't see words any differently than an efficient reader might. Yes they are more prone to mix their 'b' and 'p' or read the word 'top' when in fact the word 'pot' appears on the page, but they aren't flipping the letters or word so much as they just have trouble identifying and retrieving them from memory. 

In exceptional cases, some dyslexics may see words moving around or other visual distortions,  but this isn't the norm.

The National (US) Center for  Learning Disabilities: Defining Dyslexia

What is Dyslexia:
Global Perspectives

For full text definitions of dyslexia from leading dyslexia, health, learning and reference organizations, see our definitions page.

Phonological awareness

Phonological awareness refers to the ability to identify and manipulate the sounds of language. It includes the ability to distinguish sounds, count syllables and identify rhymes. For example: which sound do you hear at the start of the words food and find? Or, how many syllables are there in the word caterpillar? Or, which of the following words does not rhyme: log, dog, bog, car?

Phonological awareness refers only to speech sounds, so technically you could do it without knowledge of the alphabet. In fact you could have excellent phonological awareness without having ever seen a printed letter!

Remarkably, there is an entire website dedicated to the concept of phonological awareness. It's a helpful source of phonological awareness activities for young readers.


Phonology: The branch of linguistics concerned with the systematic organization of sounds of language. Think ears!

Phonological awareness
is the ability to identify and manipulate sounds. It includes identification of different words, recognition of syllables (count the beats...) and rhymes.

Phonemic awareness is a subset of phonological awareness referring specifically to the identification and manipuation of phonemes, of which there are 44 in English. It includes the abilty to make rhymes, blend and manipulate phonemes and spell. For example... If I remove the 's' from the word stop, what word do I have?

These last two terms are often used interchangeably, but they shouldn't be.

Phonemic awareness

Phonemic Awareness, is a subset of phonological awareness, meaning that it is also about the ability to identify and manipulate sounds. But in this case, it is more specific, referring to the ability to identify and manipulate the smallest sound units of a language. Like phonological awareness, phonemic awareness is possible without knowledge of the alphabet or written words, but in practice phonemes are usually taught using a combination of spoken and written text (including using tiled letters). 

What's a phoneme?

A phoneme is the smallest unit of speech sound that can convey a unique meaning. In English there are 44 unique sounds or phonemes. These are the critical building blocks of language that dyslexics have a lot of difficulty manipulating when it comes time to read or write and even speak. 

Beyond a definition

We surveyed the definition of dyslexia offered by every dyslexia, health, learning and reference institution that we could find . We found some helpful elements that add to our definition, but also a number of very bad definitions that ranged from motherhood statements to advocacy.

Below is a summary of the best of our findings.

What is Dyslexia?

Dyslexia IS...

Dyslexia IS NOT...

  • Extreme difficulty reading

  • A specific learning disability

  • Brain based (neurobiological)

  • Inherited (genetic)

  • Poor ability to manipulate phonemes

  • Poor spelling ability

  • Poor decoding ability

  • Poor word recognition

  • Poor reading comprehension

  • Poor verbal memory and processing speed

  • Often unexpected relative to other cognitive abilities

  • Often correlated with difficulties in motor co-ordination, mental calculation, concentration and personal organization

  • Composed of sub-types, some of which benefit from specialized interventions

  • Recently shown to be linked to a number of specific genes that may predispose an individual to develop the disability
  • Not the result of low intelligence

  • Not the result of environmental influences during pregnancy

  • Not caused by Attention Deficit Hyperactivity Disorder (Athough many people with dyslexia also have ADHD)

  • Not caused by reversing or flipping letters

  • Not a result of seeing letters and words backwards

  • Not primarily a visual problem

  • Not something that one will will naturally 'grow out of'

  • Not a disease

  • Not rare

  • Not characterized as a medical problem

  • Not curable (but very treatable)

  • Not a gift imparting special savant abilities. But there is some science based evidence that dyslexics may be above average in certain niche skills, including visual spatial and artistic abilities

  • Not particular to one language, gender, ethnicity or geographic location

Linkages with the other "Dys's"

Those with dyslexia also often struggle with ADHD, dysgraphia, dyscalculia, and dyspraxia.  At first these sister challenges seem like unrelated, cruel coincidences but a closer look reveals some common underlying causes: difficulty sustaining focused attention (both hyper or inattentive types), problems with short term and working memory and slower or less efficient cognitive processing—all of which are often exacerbated by anxiety.

With patience, encouragement and determination each challenge can be met, but collectively they represent a heavy burden for any child trying to succeed in a modern school system and eventually, in the information economy. In turn this puts additional responsibility on parents and teachers to rise to the challenge of equipping these students with the skills, abilities and self confidence necessary to succeed. The purpose of this site is to help in that task.

What is dyslexia: final thoughts

Although an understanding of dyslexia is complicated by its linkages to related challenges in attention, anxiety, writing, motor coordination and mathematics, at it's heart, dyslexia is simply difficulty reading.

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