In Egyptian, it takes the forms -j, whereas in Semitic it takes the form -i(y); it thus has the same form in both language families. The Semitic genitive case in -i is probably related to "nisba" adjective derivation. Due to its presence in the oldest attested and best-known AA branches, nisba derivation is often thought of as a "quintessentially Afroasiatic feature". Christopher Ehret argues for its presence in Proto-Afroasiatic and for its attestation in some form in all branches, with a shape -*ay in addition to -*iy in some cases. Vocabulary comparison Pronouns The forms of the pronouns are very stable throughout the Afroasiatic (excluding Omotic), and they have been used as one of the chief tools for determining whether a language belongs to the family. However, there is no consensus on what the reconstructed set of Afroasiatic pronouns might have looked like. A common characteristic of AA languages is the existence of a special set of "independent" pronouns, which are distinct from subject pronouns. They can occur together with subject pronouns but cannot fulfill an object function. Also common are dependent/affix pronouns (used for direct objects and to mark possession). For most branches, the first person pronouns contain a nasal consonant (n, m), whereas the third person displays a sibilant consonant (s, sh). Other commonalities are masculine and feminine forms used in both the second and third persons, except in Cushitic and Omotic. These pronouns tend to show a masculine "u" and a feminine "i". The Omotic forms of the personal pronouns differ from the others, with only the plural forms in North Omotic appearing potentially to be cognate. Numerals Unlike in the Indo-European or Austronesian language families, numerals in AA languages cannot be traced to a proto-system. In the Chadic family alone, there are two different roots for "two," and Berber and Semitic likewise have two different branch-internal roots for "two". Within the Semitic language family, Lipiński counts four different roots meaning "one". Modern Chadic numeral systems are sometimes decimal, having separate names for the numbers 1-10, and sometimes base-5, deriving the numbers 6-9 from the numbers 1-5 in some way. Andrzej Zaborski further notes that the numbers "one," "two," and "five" are particularly susceptible to replacement by new words, with "five" often based on a word meaning "hand". Another factor making comparisons of AA numeral systems difficult is the possibility of borrowing. Only some Berber languages maintain