Adjective
1. designating or involving an equation whose terms are of the first degree
2. of or in or along or relating to a line; involving a single dimension;
"a linear foot"3. of a circuit or device having an output that is proportional to the input;
"analogue device""linear amplifier"4. of a leaf shape; long and narrow
5. measured lengthwise;
"cost of lumber per running foot"