通す【とおす】

通す after a verb's ます-stem means "keep doing it all the way through": the action runs to the end without stopping or giving up. The result is an ordinary godan verb – やりとおすやり通す, やりとおしたやり通した, やりとおさないやり通さない.

The verb goes in the ます-stem, not the dictionary form: ×走る通す.

Without a break

With a stretch of time, 通す says the action filled all of it.

Holding to a position

With a belief, an opinion or a lie, 通す means keeping it up to the end against pressure.

Usage notes

These go beyond the verb 通す.

The noun ～通し

The ます-stem plus とおし通し, read どおし, is a noun: "doing it the whole time". It takes だ and is used mostly with standing, walking and working.

通す or 抜く

やりぬくやり抜く also means "see it through", with the stress on beating the difficulty. 通す stresses that the action never stopped.