A decent number of studies have discussed phonological or morphological aspects of the definite article in Standard or Classical Arabic. However, only a few have described the definite article in Southern Arabic dialects. Arabic consonants are divided into two categories based on how they affect the definite article al-[ʔal-]. Fourteen consonants with the [+coronal] feature cause assimilation, whereas the remaining consonants with [-coronal] do not. This process raises the question of whether this is also the case with the definite article [ʔam-] of the Southern dialect Jazani Arabic. Thus, one goal of this study was to examine whether assimilation occurs in the first place with [ʔam-]. If so, does it assimilate to consonants with specific features? Does it fully or partially assimilate to other consonants? Does directionality play a role in assimilation? Enlightened by autosegmental phonology and feature geometry, this study presents a novel dataset and a non-linear phonological analysis of Jazani [ʔam-] via linking or delinking features. Results showed that [ʔam-] completely assimilated and caused geminates when followed by [m] and partially assimilated when followed by [b] or [w] but never after [-labial] sounds. Assimilation occurred progressively or regressively based on the sonority hierarchy of the consonants. In addition, assimilation only occurred across morphological boundaries and never within one morpheme. [ABSTRACT FROM AUTHOR]