The Collaborative International Dictionary of English v.0.48:

Koran \Ko"ran\ (k[=o]"ran or k[-o]*r[aum]n"; 277), n. [Ar.
   qor[=a]n; with the Ar. article, Alkoran, Alcoran; = Turk.
   Pers. qur[^a]n, from Ar. quran, qoran, book, reading, from
   q[^a]r[^a], read. See Alcoran.]
   The Scriptures of the Muslims, containing the professed
   revelations to Mohammed; -- called also Alcoran. [Written
   also Kuran or Quran, Also rarely Coran and Core.]

   Note: The Koran is the sacred book of the Muslims (sometimes
         called Mohammedans by non-Muslims, a term considered
         offensive by some Muslims). It is the most important
         foundation on which Islam rests and it is held in the
         highest veneration by all Islamic sects. When being
         read it must be kept on a stand elevated above the
         floor. No one may read it or touch it without first
         making a legal ablution. It is written in the Arabic
         language, and its style is considered a model. The
         substance of the Koran is held to be uncreated and
         eternal. Mohammed was merely the person to whom the
         work was revealed. At first the Koran was not written,
         but entirely committed to memory. But when a great many
         of the best Koran reciters had been killed in battle,
         Omar suggested to Abu-Bekr (the successor of Mohammed)
         that it should be written down. Abu-Bekr accordingly
         commanded Zeid, an amanuensis of the prophet, to commit
         it to writing. This was the authorized text until 23
         years after the death of the prophet. A number of
         variant readings had, however, crept into use. By order
         of the calif Osman in the year 30 of the Hejira, Zeid
         and three assistants made a careful revision which was
         adopted as the standard, and all the other copies were
         ordered to be burned. The Koran consists of 114 suras
         or divisions. These are not numbered, but each one has
         a separate name. They are not arranged in historical
         order. These suras purport to be the addresses
         delivered by Mohammed during his career at Mecca and
         Medina. As a general rule the shorter suras, which
         contain the theology of Islam, belong to the Meccan
         period; while the longer ones, relating to social
         duties and relationships, to Medina. The Koran is
         largely drawn from Jewish and Christian sources, the
         former prevailing. Moses and Jesus are reckoned among
         the prophets. The biblical narratives are interwoven
         with rabbinical legends. The customs of the Jews are
         made to conform to those of the Arabians. Islamic
         theology consists in the study of the Koran and its
         commentaries. A very fine collection of Korans,
         including one in Cufic (the old Arabic character), is
         to be found in the Khedival Library at Cairo, Egypt.
         [Century Dict. 1906]

WordNet (r) 3.0 (2006):

Koran
    n 1: the sacred writings of Islam revealed by God to the prophet
         Muhammad during his life at Mecca and Medina [syn: Koran,
         Quran, al-Qur'an, Book]

The Devil's Dictionary (1881-1906):

KORAN, n.  A book which the Mohammedans foolishly believe to have been
written by divine inspiration, but which Christians know to be a
wicked imposture, contradictory to the Holy Scriptures.