latitudinarian adj.

late 14c., "breadth," from Old French latitude (13c.) and directly from Latin latitudo "breadth, width, extent, size," from lātus (adj.) "wide, broad, extensive" Old Latin stlatus, from PIE *stleto-, suffixed form of root *stele- "to spread, to extend" (source also of Old Church Slavonic steljo "to spread out," Armenian lain "broad").

Geographical and astronomical senses also are from late 14c., literally "breadth" of a map of the known world. Figurative sense of "allowable degree of variation, extent of deviation from a standard" is early 15c. Related: Latitudinal "pertaining to geographic latitude" (1777); latitudinous "having broadness of interpretation" (1829, American English).

The ancients supposed the torrid and the frigid zones to be uninhabitable and even impenetrable by man, but while the earth, as known to them, was bounded westwardly by the Atlantic Ocean, it extended indefinitely towards the east. The dimensions of the habitable world then (and ancient geography embraced only the home of man ....,) were much greater, measured from west to east, than from south to north. Accordingly, early geographers called the greater dimension, or the east and west line, the length, longitudo, of the earth, the shorter dimension, or the north and south line, they denominated its breadth, latitudo. These Latin terms are retained in the modern geography of most European nations, but with a modified meaning. [George P. Marsh, "Lectures on the English Language," 1882]

1640s, "belonging or pertaining to a schismatic sect," applied by Presbyterians to Independents, from Medieval Latin sectarius, from secta "religious group, sect in philosophy or religion" (see sect). By 1796 as "of or pertaining to sects or to attachment to a particular sect; including the tenets of a sect," hence "bigotedly attached to a sect." Sectarial (1816) is "Chiefly used with reference to Indian religions" [OED].

As a noun, "one of a sect" (1650s), especially "one who attaches excessive importance to a sect." The older word in this sense is sectary.