Lewis & Short

līnĕāris, e (or līnĭāris), adj. [linea], of or belonging to lines, consisting of lines, linear: pictura, the art of drawing with lines, without colors, Plin. 35, 3, 5, § 16: ratio, the science of lines, geometry, Quint. 1, 10, 36: probatio, a proving by means of lines, a mathematical demonstration, id. 1, 10, 49.
Adv.: līnĕārĭter, by lines, Boëth. Inst. Music. 3, 9 init.