To pierce through or go through physically; to penetrate or perforate something.
矢が鎧を貫き通した。
The arrow pierced right through the armor.
稲妻が雲を貫き通したように見えた。
It looked as if lightning had pierced through the clouds.
To stick to or carry out an opinion, principle, or policy to the end; to persist in or uphold something resolutely.
彼は自分の信念を最後まで貫き通した。
He stuck to his beliefs until the end.
会社は創業時の理念を貫き通すと宣言した。
The company declared it would uphold its founding principles.
その方針を貫き通すには多くの努力が必要だ。
It takes a lot of effort to maintain that policy consistently.