thorn cluster
noun1
Human sciences, Linguistics, Sciences One of three consonant clusters historically believed by some scholars to have existed in Proto-Indo-European, all of which ended with the IPA sound /θ/ (then often symbolized as þ).
2
Human sciences, Linguistics, Sciences Any of the reconstructed consonant clusters that have replaced the original thorn clusters in modern scholarship, which typically no longer contain the IPA /θ/.