WordNet (r) 3.0 (2006):

writing system
    n 1: a method of representing the sounds of a language by
         written or printed symbols [syn: orthography, writing
         system]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "writing system":
   Arabic, Armenian, Assyrian, Avestan, Babylonian, Berber,
   Chalcidian, Cherokee, Coptic, Cretan, Cyrillic, Elamitic, Etruscan,
   Georgian, Gothic, Greek, Hebrew, IPA, ITA, Iberian,
   Initial Teaching Alphabet, International Phonetic Alphabet, Irish,
   Kalmuck, Korean, Latin, Lemnian, Libyan, Linear A, Linear B,
   Lycian, Lydian, Manchu, Mayan, Minoan, Mitannic, Mongolian, Nubian,
   Oscan, Pahlavi, Permian, Persian, Phoenician, Phrygian, Sanskrit,
   Scandinavian, Semitic, Sinaitic, Sogdian, Sumerian, Szeklian,
   Tuareg, Uighur, Umbrian, Vietnamese, alphabet, alphabetics,
   futhark, graphemics, hiragana, kana, kanji, katakana, letter,
   letters, ogham, paleography, punctuation, runic, runic alphabet,
   script, syllabary, written character



The Free On-line Dictionary of Computing (30 December 2018):

writing system

    The set of glyphs used for
   representing a given human language in written form, generally
   along with their conventions for use.

   (1998-10-19)