https://www.lesswrong.com/posts/WBw8dDkAWohFjWQSk/the-cluster-structure-of-thingspace [LW · GW]

Words point to clusters of similar things. If we just want to point in the rough direction of a cluster, use a general term like "AGI", if you want to talk about a more well defined and specific set, you can say things like "an AI that can do all tasks related to AI research at least as well as a top human researcher".

Also, words are pointing to empirical clusters, so fictional examples might not be in any of the real world clusters. Real world animals are clustered into mammal, bird, reptile ect. But some fictional animals like gryphons don't fit in that classification.