Neuric

Neuric is a contextual metalanguage; whenever a word is spoken or signed in the New Real, regardless of the language the speaker uses, it is given context from the person's memory.

For example, saying the word Bus to someone who is not a speaker of English would normally result in confusion. With Neuric, saying or signing a word also broadcasts a memory of what the word means, so the listener will feel that a bus is a large horseless carriage used as a method of mass transit, including implications of what mass transit is and why it would be useful to the speaker.

This simple system results in fast, universal transmission of information with no misunderstandings. Most people in the New Real speak the languages they knew in life peppered with the first foreign word they ever heard to describe something they were unfamiliar with.

But everyone speaks English in the books!
On a metafictional level, conversations in the novels are only written in English for the sake of the reader and writer, not due to actual fluency in English on the part of the characters.