noun
General term for a tunnel, such as a road or railway tunnel.
電車が長いトンネルに入った。
The train entered a long tunnel.
noun or participle which takes 'suru'
tunnel through a potential barrier
Physics term for quantum tunneling. Used with する.
電子が障壁をトンネルする現象をトンネル効果という。
The phenomenon of an electron tunneling through a barrier is called the tunnel effect.
noun, noun or participle which takes 'suru'
letting a grounder go through one's legs
Baseball term for a fielding error where a ground ball passes between a fielder's legs. Often used as トンネルする.
ショートがトンネルしてランナーが出塁した。
The shortstop let the ball go through his legs, and the runner reached base.