linear

adjective

1. Having the form of a line; straight or roughly straight; following a direct course.
2. Of or relating to lines.
3. Made, or designed to be used, in a step-by-step, sequential manner.
4. Long and narrow, with nearly parallel sides.
5. Having degree one; that is, being of the form a_1x_1+a_2x_2+⋯+a_nx_n+b, where each x_i is a variable. See also Linear polynomials on Wikipedia.Wikipedia
6. Involving only linear polynomials. See also Linear equation on Wikipedia.Wikipedia
7. An additive, homogeneous mapping; that is, a function f:V→W is linear if it distributes over vector addition (f( mathbf v+ mathbf w)=f( mathbf v)+f( mathbf w)) and respects scalar multiplication (f(c mathbf v)=cf( mathbf v)). If V and W are vector spaces over a field K, f may also be called a K-linear map. See also linear map on Wikipedia.Wikipedia
8. A module homomorphism; that is, a group homomorphism that commutes with scalar multiplication. See also Module homomorphism on Wikipedia.Wikipedia
9. A type of length measurement involving only one spatial dimension (as opposed to area or volume).
10. Delivered or delivering on a fixed schedule, as opposed to on-demand.