Methodology: creating and testing the dictionary

To create Learn These Words First, the 2352 definitions in the NSM-LDOCE dictionary were sequenced into layers using the recursive-dependency statistics from the "Non-Circular Dictionary" study. Then each definition was edited for greater fluency and precision, utilizing words available in the preceding layers.

Using computer-aided paraphrase, the number of "semantic molecules" was reduced to around 300 words. These words, preceded by the NSM vocabulary, were grouped into 12 lessons and expanded to use full-sentence definitions and examples.

Student participants performed headword-identification tasks to evaluate the quality of every definition in the Learn These Words First lessons. For fill-in-the-blank tasks (given definitions without headwords), students correctly identified the missing headword 95% of the time. For complete-the-word tasks (given definitions and only the first letter of each headword), students identified the headword 100% of the time.

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Research behind the dictionary

Learn These Words First implements a layered monolingual dictionary.

The first layer (Lessons 1 and 2) consists of words representing 61 universal concepts expressed in all languages. This set of "semantic atoms" is based on the Natural Semantic Metalanguage (NSM), developed over the last three decades by Anna Wierzbicka and Cliff Goddard.

• Wierzbicka, Anna. 1996. Semantics: Primes and Universals. Oxford: Oxford University Press.
• Goddard, Cliff and Anna Wierzbicka (eds.). 2002. Meaning and Universal Grammar - Theory and Empirical Findings. Volumes I and II. Amsterdam: John Benjamins.

The 34 middle layers consist of 300 "semantic molecules" (Lessons 3 through 12). Words in each layer are defined using only the words from the previous layers. This sequence of layers is based on dependency-graph analysis of the non-circular NSM-LDOCE research dictionary.

• Bullock, David. 2011. "NSM + LDOCE: A Non-Circular Dictionary of English" in the International Journal of Lexicography. Oxford: Oxford University Press, 24.2: 226-240.

The next layer in Learn These Words First is an alphabetical reference section containing definitions for the 2000 words in the Longman Defining Vocabulary, each defined using only the 360 "atoms" and "molecules" from the lessons.

(The Longman Dictionary of Contemporary English can be considered the final layer, since every word is defined using only the 2000-word defining vocabulary.)

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What is a Multi-Layer Dictionary?

Most dictionaries have two layers:

• The long alphabetical list of all headwords and their definitions.
• The "defining vocabulary" = the words used to write all the definitions.

To understand a dictionary's definitions, you need to understand the words in the defining vocabulary. Since a typical learner's dictionary has a defining vocabulary containing 2000 or more words, you must already have at least an intermediate-level vocabulary to use the dictionary.

In a multi-layer dictionary, like Learn These Words First, definitions are arranged in layers so they can be understood by learners with different levels of vocabulary:

• Basic vocabulary: The most basic words are explained for beginning-level learners, using illustrations, translations, etc. These words are presented in a series of short lessons.
• Defining vocabulary: These intermediate-level words are explained using only the words from the basic vocabulary lessons.
• Full dictionary: This includes advanced-level words, all explained using only the defining vocabulary.

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