A new research paper has just been released on the Loops and Self-Reference in the Construction of Dictionaries. The authors looked at the words in a database called WordNet, treating them as nodes in a graph structure connected by directional links (that is, the link points to words used in the definition). Levary et al. show both theoretically and from watching how nodes are incorporated into the graph that new concepts can only be introduced by adding a loop to the network. They also discovered that words in a given loop often were introduced into the language at about the same time. When the dates of origin of words in a loop differ greatly, it typically indicates a fundamental change in a word’s meaning after its earlier introduction. Download the paper.