parallel rule

noun

variants or parallel ruler

: an instrument for drawing a line parallel to another or a series of parallel lines: such as

a

: a flat rule running on a pair of rollers in one of its sides

b

: a pair of straightedges connected by two equal parallel links so that one straightedge can be moved only parallel to the other

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!