linear (Adjective) — (mathematics) designating or involving an equation whose terms are of the first degree.
linear (Adjective) — Of, in, along or relating to a line; involving a single dimension. ex. "a linear measurement"
linear (Adjective) — (electronics) Of a circuit or device in which the value of a data item is represented by a continuously variable physical quantity rather than digitally. ex. "linear amplifier"
linear (Adjective) — (of a leaf shape) long and narrow.
linear (Adjective) — Measured lengthwise. ex. "cost of lumber per linear foot"