# i+1

> English word · Adjective

## Definitions
1. Containing only a single word unknown to the listener or reader.

## Etymology
Ostensibly coined by Stephen Krashen in his Explorations in Language Acquisition and Use in 2003; but possibly earlier. Originally, referred to a subsequent word (the 1) added to an existing vocabulary of i words, i.e. the i+1th word learned by the learner.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/i-1