Semitic languages
The similarity of the Hebrew, Arabic and Aramaic languages was accepted by Jewish and Islamic scholars since medieval times. The languages were familiar to Western European scholars due to historical contact with neighbouring Near Eastern countries and through Biblical studies, and a comparative analysis of Hebrew, Arabic, and Aramaic was published in Latin in 1538 by Guillaume Postel. Almost two centuries later, Hiob Ludolf described the similarities between these three languages and the Ethiopian Semitic languages. However, neither scholar named this grouping as "Semitic".
Biblical Hebrew
Broken plural forms in Arabic are declined like singulars, and often take singular agreement as well. Dual and "strong plural" forms use endings with a long vowel or diphthong, declined in only two cases: nominative and objective (combination accusative/genitive), with the objective form often becoming the default one after the loss of case endings. Both Hebrew and Arabic had a special form of nunation/mimation that co-occurred with the dual and masculine sound plural endings whenever the noun was not in the construct state. The endings were evidently felt as an inherent part of the ending and, as a result, are still used. Examples are Arabic strong masculine plural "-ūna" (nominative), "-īna" (objective), and dual endings "-āni" (nominative), "-ayni" (objective); corresponding construct-state endings are "-ū, -ī" (strong masculine plural), "-ā, -ay" (dual). (The strong feminine endings in Classical Arabic are "-ātu" nominative, "-āti" objective, marked with a singular-style "-n" nunation in the indefinite state only.)