undergrounds

1. 1
   noun

   Plural of underground.

   Engineers compared the London and Paris undergrounds before drafting the new transit plan.

   Wartime resistance undergrounds passed messages through a network of trusted couriers.

   Note

   A regular -s plural that earns its keep when there is more than one countable thing: separate rail systems, or separate resistance networks. The railway meaning is British, with subway as its synonym. The movement meanings usually take the definite article, as in the underground. A plural therefore signals distinct networks set side by side, not the movement as a whole.

2. 2
   verb

   Third-person singular simple present indicative of underground.

   The utility undergrounds its distribution lines wherever wildfire risk is high.

   Each spring the council undergrounds another stretch of overhead cable along the coast road.

   Note

   Behind this form is a narrow, technical verb. To underground something is to route electricity distribution cables below the surface, so its object is lines or cable. The same spelling also serves as the plural noun, but position tells them apart: here a subject comes first. Writers who avoid the verb use the adverb instead and say a utility puts its lines underground.

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