Generalising from fdb's answer about Arabic and postmortes' answer about Maltese: there are several languages in the Semitic family that have these three properties. Inflected nouns and adjectives are in Proto-Semitic, but definiteness was not a morphological category at that stage. However, some languages developed prefixes and suffixes for this purpose (Hebrew, Arabic, Aramaic, Amharic):
Definiteness seems not to have been a morphological category of Proto-Semitic. Akkadian does not indicate definiteness at all, and Ge'ez only in an incipient or covert way. In those languages which do have a definite article, the formal variation is striking. The article, though always affixal, is a prefix in some languages, a suffix in others. Thus Hebrew has the prefix ha-, Arabic has the prefix al-, whereas Aramaic uses the suffix -ā and South Arabian has the suffix -n. Amharic has innovated a new definite suffix -u from the old 3sg possessive clitic ‘his’ (see 2.). Nouns which have a pronominal possessive suffix, or which occur in the Construct form (and thus take a following dependent genitive), do not take the article. An indefinite article is found only in Arabic, where its suffixal form (nunation: -n) contrasts with the prefixal definite article al-, so that ‘definiteness’ is expressed in two different slots:
al-kitābu ‘the book’ vs. kitābu-n ‘a book’.
(Note that -n is an indefinite marker in Arabic, but a definite marker in South Arabian.)
Weninger, S., Watson, J. E., Streck, M. P., & Khan, G. (2011). The Semitic Languages: An International Handbook. Berlin: De Gruyter Mouton.
Hence, it appears that the definite article has been a separate development in several branches of West Semitic (at least Arabian, North-West Semitic and Ethiosemitic). However, Amharic inflects the article so the non-inflected definite article seems to be restricted to Central Semitic.