The present paper is dedicated to Italian adjective-adjective sequences as a borderline phenomenon oscillating between morphology and syntax. AA sequences with a linking vowel -o- and a single morphological locus for agreement at the end of the sequence are undoubtedly morphological in nature, while the distinction between asyndetic AA compounds and coordinative AA phrases is a tricky matter, depending solely on semantics. The paper shows how the asyndetic compound-type arose besides the one with a linking vowel, taken over from Neo-Latin in the 17th century and characterises their mutual relationship in present-day Italian in terms of blocking. Some restrictions and ordering preferences in modern Italian are argued to reflect this Neo- Latin origin. And finally, the phenomenon of apocope of the type imperialregio, specific to Italian, is interpreted as an iconic strategy to achieve greater formal integration in asyndetic AA compounds.