They hope to make big 'gains' in Congress in the coming election. [=they hope that many more members of their party will be elected to Congress]
Her hard work 'gained' her their respect. [=she has gained their respect through hard work; they respect her now because of her hard work]
a stock that was one of the year's biggest 'gainers' [=one of the stocks that increased the most in value]
(..) we've worked in vain. No, go on. Nothing special as usual. They stuff you with pills. You leave that place after losing kg, which you gain back after the first glass of wine. Exhausted and without money. There. I smell a rat-a-big. What about you? - Nothing special. - Except what? (..)1981 To Kill a Cop