tunnelling

verb

1. (UK, form-of, gerund, participle, present)present participle and gerund of tunnel

   “As it was necessary to reconstruct the culvert close to the original position, the hazards of tunnelling through clay in an unstable condition, due to the absorption of water, had to be reduced by the application of electro-osmosis to dry out the material.”

noun

1. (alt-of, alternative, countable, uncountable)Alternative form of tunneling.