The word 'tract' entered English in the late 14th century from the Latin 'tractus', meaning "a drawing out, extension, course, space, or duration." This Latin noun derives from the past participle stem of the verb 'trahere', meaning "to pull, draw." The core semantic thread from the Proto-Indo-European root tragh- ("to draw, drag, move") is the idea of something drawn out or extended. This logic explains the modern meanings: a 'tract' of land is an extended area; a bodily 'tract' is an extended system of connected parts; and a written 'tract' is an extended discourse on a subject, originally implying something "drawn out" in length.

The entire word 'tract' is a simplex morpheme. It is a loanword from Latin, where 'tractus' meant "a drawing out, extension, course." It functions as a noun-forming root in English.