Bluelines

Part of speech: noun

Definitions

1. Lines that are used in artistic or design contexts, often serving as guides or boundaries for creating blueprints or drafts
2. a reference to the visible ink or markings in blue used for drafting or notation in various fields
3. a term for the lines of demarcation that assist in layout or alignment during the creative process

Etymology: Bluelines are named for the colour of the ink, not for anything about the lines themselves. In the older photographic printing trade, a proof was made by exposing light-sensitive paper through a film of the artwork, and the resulting print came out with image and guide marks in blue. Printers and designers used those blue marks as a reference for trimming, folding and aligning the final job, and the blue lines themselves were the non-printing guides that showed where the page edges and fold marks would fall. The word is a plain compound of "blue" and "line", with nothing hidden in it. Its plural form simply names more than one such guide on a proof or layout. The meaning has stayed close to the literal one: a blue line marks a boundary the printer can see and work to, even as the process behind it has changed.