【意味】
～に反対して,～に対して

【用例】
He swam against the tide.
(彼は潮の流れに逆らって泳いだ。)

Some people are for the new tax and others are against it.
(新しい税に賛成の者もいれば反対の者もいる。)

I'm against to his opinion.
(彼の意見には反対だ。)

He hit his head against the wall.
(彼は壁に頭をぶつけた。)