Full Idea
We don't need 'essences' or 'criteria' to keep the meaning of our word from sliding all over the place; our words will stay put, quite firmly attached as if by gravity to the nearest similarity cluster.
Gist of Idea
Words are fixed by being attached to similarity clusters, without mention of 'essences'
Source
Daniel C. Dennett (Consciousness Explained [1991], 13.2)
Book Reference
Dennett,Daniel C.: 'Consciousness Explained' [Penguin 1993], p.421
A Reaction
Plausible, but essentialism (which may have been rejuventated by a modern theory of reference in language) is not about language. It is offering an explanation of why there are 'similarity clusters. Organisms are too complex to have pure essences.