Core words are what we also call high frequency words. This means that, through extensive research of people’s natural speech it was found that 80% of the time we use the same basic “core words.” This list of core words is made up of a list of basic words that number in the hundreds.
The other words that we use, we call fringe vocabulary or extended vocabulary. These are only used 20% of the time.
In creating an AAC system, people sometimes call whatever words they choose to put on the system the child’s “core vocabulary” even if those words are mainly personal names, specific toys, special places or foods. Doing this may give you the impression that the board is great, as it has been customised for the the child, but actually you are limiting the child’s vocabulary by giving them mainly “fringe” words. Your child will then not have access to the words that are used 80% of the time and will struggle to communicate with others, build sentences and develop language.
This is a little video to illustrate the importance of core words.