From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( v.) Treatment; exposition.

(2): ( v.) A region or quantity of land or water, of indefinite extent; an area; as, an unexplored tract of sea.

(3): ( v.) Something drawn out or extended; expanse.

(4): ( n.) A written discourse or dissertation, generally of short extent; a short treatise, especially on practical religion.

(5): ( v.) The footprint of a wild beast.

(6): ( v.) Traits; features; lineaments.

(7): ( v.) Track; trace.

(8): ( v.) Continued or protracted duration; length; extent.

(9): ( v.) Verses of Scripture sung at Mass, instead of the Alleluia, from Septuagesima Sunday till the Saturday befor Easter; - so called because sung tractim, or without a break, by one voice, instead of by many as in the antiphons.

(10): ( v. t.) To trace out; to track; also, to draw out; to protact.

(11): ( v.) Continuity or extension of anything; as, the tract of speech.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]

a psalm, or portion of a psalm, sung in the Latin mass instead of the Gradual, on fixed days; from Septuagesima to Easter, after the Epistle. At the time at which the Church is commemorating the passion of our Lord, this Tract is slowly chanted in lieu of the joyous Gradual. It is called the Tract, as some ritualistic writers affirm, because it is drawn out in a slow and solemn strain. It is said that the psalm or hymn chanted by one voice was the Tract, and when the singer was interrupted by the choir his part was known as the versicle, and the portions allotted to them were called responsories. See Lee, Gloss. of Liturg. Terms, s.v.; Walcott, Sac. Archaeol. s.v.