noun: an uninflected function word that serves to conjoin words or phrases or clauses or sentences
noun: (astronomy) apparent meeting or passing of two or more celestial bodies in the same degree of the zodiac
noun: the grammatical relation between linguistic units (words or phrases or clauses) that are connected by a conjunction
noun: something that joins or connects
noun: the state of being joined together
noun: the temporal property of two things happening at the same time

Ramsay
The law of gravitation is the law of Music as well as of Astronomy. The cycles of the distances, that is the intervals, in Music correspond to the cycles of the periods in Astronomy. In Astronomy the distances and quantities of matter are primary, and determine the periods; in Music the periods and quantities are primary, and determine the distances or intervals. In Astronomy the distances are commensurable; in Music the periods are commensurable. In Astronomy the periods are incommensurable; in Music the distances or intervals are incommensurable. In Astronomy, because the simplicity is not in the periods, the conjunctions are very few at one time; in Music, because the simplicity is in the periods, the conjunctions are very many at one time. And herein lies in the one case the harmony and permanence of the solar system, and in the other case the harmony and beauty of the musical system. The periods and distances in Astronomy and Music are inversely related. [Scientific Basis and Build of Music, page 30]