(adj) coming next after the third and just before the fifth in position or time or degree or magnitude, Syn. 4th, quaternary, Example:the quaternary period of geologic time extends from the end of the tertiary period to the present
(n) the Lateran Council in 1215 was the most important council of the Middle Ages; issued a creed against Albigensianism, published reformatory decrees, promulgated the doctrine of transubstantiation, and clarified church doctrine on the Trinity and Incarnation
n. 1. One of four equal parts into which one whole may be divided; the quotient of a unit divided by four. [ 1913 Webster ]
2. (Mus.) The interval of two tones and a semitone, embracing four diatonic degrees of the scale; the subdominant of any key. [ 1913 Webster ]
3. One coming next in order after the third. [ 1913 Webster ]
The Fourth, specifically, in the United States, the fourth day of July, the anniversary of the declaration of American independence; as, to celebrate the Fourth. [ 1913 Webster ]