Formal:
* Illiterate: This is the most formal and accurate term for someone who cannot read or write at all.
* Functionally illiterate: This term describes someone who can read and write at a basic level but struggles with more complex tasks like reading a newspaper or filling out a job application.
* Low literacy: This is a general term that encompasses people with various levels of reading and writing difficulty.
Informal:
* Struggling reader: This is a more general term that doesn't necessarily imply complete illiteracy.
* Poor reader: Another informal term that suggests difficulty with reading.
* Unskilled in literacy: A less common but accurate way to describe someone who lacks reading and writing skills.
Other terms:
* Learning disabled: This is a broad term that covers a wide range of disabilities, including those that may affect reading and writing.
* Dyslexic: This term refers to a specific learning disability that affects reading skills.
The best word to use depends on the specific situation and the level of formality required. It's important to be respectful and understanding when talking about someone's literacy abilities.