The aim of this paper is to offer an analysis of the well-known metathesis process of the sibilant+dental stops clusters in the reflexive/passive verbal forms of Ancient Aramaic and Ancient Hebrew. This process will not be considered as a proper feature of Aramaic and Hebrew: it will be integrated into the more general discussion on extrasyllabicity and on special status of the coronal obstruents at word edges.
In order to support my analysis, other data will be discussed. Firstly, the Classical Arabic verbal form IX does not exist in the Aramaic and Hebrew verbal system. The reason will be exposed, according to my hypothesis. Secondly, the complete assimilation of the lateral consonant l of the Classical Arabic definite prefix 'al- takes place only when the first consonant of the noun is a coronal (including sonorant r, n): a draft of an analysis will be presented, showing again the link between word edges and coronal consonants.