Nun is the fourteenth letter of the Syriac abjad, with the numeral value fifty. It writes n, a voiced alveolar nasal. It joins on both sides and takes a distinct final form that descends below the line, which together with the tailed final kaph gives a Syriac line its lower landmarks.
Its name is the inherited Northwest Semitic word for a fish, and it holds the same fourteenth place in Hebrew.
Nun carries a great deal of Syriac grammar. The letter forms the prefix of the third person of the imperfect verb, so a very large share of the verbs in any Syriac text begin with it. That feature is one of the marks that separates Syriac and the eastern Aramaic dialects from the western Aramaic ones, which use a different prefix, and it is the sort of small grammatical fact by which a dialect is identified.
A reader therefore meets nun at the head of a word as often as inside one, and meets its descending final form at the end of a word constantly as well, since n closes many Syriac forms. Between the prefix and the ending, nun is among the most frequently written letters in the language, and its shape at the two ends of a word is quite different in each of the three hands.
Nun stands at the fourteenth place with the value fifty in Hebrew and in the Arabic abjad order as well, and its name is the word for a fish in both traditions that kept the old nouns. It is one of the correspondences that survives across all three alphabets without qualification, which is why it is a useful letter to start from when setting one Aramaic-descended alphabet beside another.