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decide against (someone or something)

1. To choose not to accept someone. Yes, Holly was a strong candidate, but we ultimately decided against her for the job.
2. To choose not to do something. I was so tired that I decided against going out with my friends tonight.
See also: decide

decide on (someone or something)

To choose someone or something, usually after a period of deliberation. Yes, Holly was a strong candidate, but we ultimately decided on someone else for the job opening. After agonizing over the menu, I finally decided on mint chocolate chip ice cream.
See also: decide, on
References in classic literature ?
The next day a letter came from two ladies who were then travelling in Italy, saying that they had decided to give us the money for such a chapel as we needed.
I'm sure you'll be safer here," Ozma decided, and the Woozy made no further objection to the plan.
After consulting together they decided that Ojo and his party should leave the very next day to search for the gill of water from a dark well, so they now separated to make preparations for the journey.
He decided to give up the pursuit, and lay down in the grass, protected right and left by the row of palms, with on either hand the long avenue extending.
After a couple more drinks, for which I insisted on paying, Nelson decided to go.
He treated us around from behind the bar, and I decided that he had arithmetically evened things up handsomely.
It isn't decided yet and perhaps we will conclude to let Mrs.
Anyhow, we've decided on the experiment and goodness only knows what will come of it.
She only remembered that Aunt Em had cautioned her to take good care of her uncle, so at once she decided to go on deck and find him, in spite of the fact that the tempest was now worse than ever, and the ship was plunging in a really dreadful manner.
Dorothy decided she must go to him; so she made a dash forward, during a lull in the storm, to where a big square chicken-coop had been lashed to the deck with ropes.
Considering the alternatives in the cab, he decided that the wise course was to temporize with Anne, by reporting matters as they then stood.
Having no decided plans for the future as yet, we returned (most unfortunately, as the event has proved) to the rooms in London which I inhabited in my bachelor days.
Trifling as this incident is in my estimation, it has decided me on one point already.
And I have decided that it is my duty to broach the subject to Leslie.
After spending two months in Moscow in a state of enchantment, seeing Kitty almost every day in society, into which he went so as to meet her, he abruptly decided that it could not be, and went back to the country.