i+1

adjective

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

“When enough comprehensible input is provided, i+1 is present.”

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Meanings

adjectivei+1 (not comparable)
  1. not comparablehuman sciencesContaining only a single word unknown to the listener or reader.

    Our SRS provides automatic i+1 sentence cards for optimal study.

nouni+1 (uncountable)
  1. uncountablehuman sciencesThe existence of only one word unknown to the reader or listener of a sentence.

    When enough comprehensible input is provided, i+1 is present.

Origin

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.

Full word history & related roots →
Cite this entry
APA

i+1. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/i%2B1

MLA

“i+1.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/i%2B1. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “i+1,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/i%2B1.

Source: i+1 on Wiktionary, CC BY-SA 4.0.