About our dictionary

What it is

When a child taps a word in one of our books, they hear it and see a short meaning written for their age. Those meanings come from our own dictionary. It has a meaning for each word in three sets of words, for ages 5 to 7, 7 to 9 and 9 to 12, with an example sentence, and it knows how each word is split into the letter sounds children are taught.

It is written in American English. Where British English spells a word differently or uses a different everyday word, a book written in British spelling gets the British version.

How the meanings are written and checked

• The meanings are written by the same software that writes our books, a few dozen words at a time.
• Each one is checked against the definition in Open English WordNet, to make sure it explains the right sense of the word, and goes through the same safety checks as a page of a book.
• A meaning that does not pass every check waits for a person on our team, and is not shown until they approve it.
• Some words are never explained without a person reading the meaning first: words about private parts of the body, violence, unkind words, and grown-up topics. Slurs and sexual words are never explained at all.
• When a child taps a word we have no meaning for, we count the word so we know what to add next. We keep the word and the number of times it was asked for, and nothing about who asked.

Where the words come from

The dictionary is built from three open datasets. We are grateful to the people who made them. Each is used under its license, and the notices those licenses ask for are below.