Formal:
* Illiterate: This is the most common and formal term.
* Non-literate: This is a more neutral term.
* Functionally illiterate: This refers to someone who can read basic words but struggles with more complex texts.
* A-literate: This is a less common term that emphasizes the absence of literacy.
Informal:
* Can't read: This is a straightforward and informal way to say it.
* Struggling reader: This is a gentler term that implies the person is making an effort to learn to read.
* Learning disabled: This is a broader term that could encompass a range of difficulties, including reading difficulties.
The best term to use will depend on the context and the audience. For example, "illiterate" is more appropriate in a formal setting, while "can't read" is more appropriate in a casual conversation.