shot in the arm
idiom

- something that has a sudden and positive effect on something, providing encouragement and new activity

(Cambridge Dictionaries)

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The expression "shot in the arm" was coined in the US and derives from the idea of an injection (shot) given in the arm for medicinal purposes, thus leading to the figurative sense of something that stimulates or causes something positive to happen.

Apart from a shot in the arm, you can do lots of other things with a shot, at least in a figurative sense:

- a cheap shot = unfairly criticise someone (That was a cheap shot!)

- a parting shot = make a remark as you are leaving somewhere (He took a parting shot at the company before jumping to the competition)

- a shot across the bow = a warning to stop doing something (The letter from the legal department was a shot across the bow)

- a shot in the dark = to try to guess something with little or no information (His theory is just a shot in the dark)

- give it your best shot = try your best (Don’t be nervous. Just give it your best shot!)

- a long shot = something with a low possibility of success (It didn’t work out, but it was a long shot anyway)

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SYNONYMS

boost, stimulant, encouragement, motivation, catalyst, incentive, energizer, impulse, spark

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SMUGGLE OWAD into today's conversation

"The latest earnings reports were a shot in the arm for the company’s stock."