Linguistics: An Introduction

By William B. McGregor



12.1 — Grassmann’s Law

Another famous sound change that happened in the history of Indo-European is called Grassmann’s Law.

Grassmann’s law describes a regular process of dissimilation that happened in Greek and Sanskrit.

If a Proto-Indo-European word had two aspirated stops the first dissimilated to an unaspirated stop (with the same point of articulation).

Greek trikhós ‘hair’ (genitive singular) derives from an earlier *thrikh-ós.

Grassmann’s Law applied to *thrikh-ós, resulting in dissimilation of the first aspirated stop to an unaspirated stop.

However, the nominative singular form of the Greek word for ‘hair’ is thríks; the kh of the root lost its aspiration due to the following segment s. (This deaspiration before s was also a regular change in the history of Greek.) Grassmann’s Law therefore did not apply, and the initial apical stop retained its aspiration.


Given the following two pre-Greek forms *threph-s-ō ‘I will rear ’ and *threph-ō ‘I rear ’, what are the expected Greek forms?


Deaspiration applies to *threph-s-ō ‘I will rear’, resulting in threp-s-ō. Grassmann’s law does not apply to this form, so we expect the modern form to be threpsō.

Deaspiration does not apply to *threph-ō ‘I rear’. This form has two apsirated stops, so Grassmann’s law applies, resulting in the deaspiration of the first. Thus the modern form will be trephō.

Updated: Feb. 11, 2009