The word line derives from the Latin linum, meaning flax plant from which linen is produced; at one time, a stretched linen thread was the most reliable way to determine a straight line.

The word line can refer to:

• a "straight line", in the geometric sense; see line (mathematics);
• a length of rope;
• a queue area;
• a line of written, printed, or spoken text;
• a product line, in marketing;
• an obsolete unit of measurement, equal to one-twelfth of an imperial inch;
• a circuit (or loop) in electrical engineering;
• a Powerline for electric power transmission;
• a telephone line;
• a measure of video display resolution or image resolution; see line (video);
• a program to emulate Linux on Microsoft Windows in the manner of WINE — see LINE;
• the line of battle in naval warfare, hence "ship of the line";
• a shipping line is a company engaged in sea transport, (from which comes the term Ocean liner);
• the infantry, as in line infantry, since foot soldiers used to pitch their tents in the field in straight lines; hence nowadays "Borneo Lines", for instance, is the name of a barracks;
• a line may refer to lineage in genealogy or evolution;
• an archaic name of the unit for magnetic flux, now named the maxwell.
• Lines (video game).
• "LINE-1" stands for "long interspersed nucleotide element-1", an abundant retrotransposon of the human genome.
• "doing a line" may refer to snorting cocaine.

fr:Droite nl:Lijn pl:Linia sl:črta