pioneer tunnel

noun
variants: or pioneer bore

Definition of pioneer tunnel

:a small tunnel parallel to a main tunnel and well in advance of the completed main tunnel so that by crosscuts to the line of the main tunnel several headings can be exposed and work expedited

There's more!

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!
Already a subscriber? Log in.

Seen and Heard

What made you want to look up pioneer tunnel? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

spoken rather than written

Get Word of the Day daily email!

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!