leaps and bounds

“leaps and bounds”という一続きのフレーズで、急成長、うなぎ登り、といった意味があります。

通常、”by leaps and bounds”、あるいは”in leaps and bounds”という形を取ることが多いですが、前置詞無しの”leaps and bounds”が副詞的に用いられることもあるようです。


LAKE STEVENS, Wash. – Costco is looking to expand with a new 170,000 square feet big-box store just inside the city limits of Lake Stevens.

It could bring jobs to a community exploding in population, but some neighbors worry that the price could mean losing what’s left of some rural neighborhoods – including a nearly 100-year-old neighborhood market.

（中略）

Lake Stevens is growing by leaps and bounds and so is the rest of the county, officials expect 200,000 more people to move into the area by 2035. So, it’s no wonder Costco wants to build a big-box store along SR 9 and 20th Street.
(Steve Kiggins. Neighbors worry Costco expansion could cost rural community. Q13 Fox. July 17, 2019. )


“leap”にしても、”bound”にしても、跳躍、跳ねる、ことですから意味合い的には納得が行きます。一種の畳語と言えるかと思います。

もう1つ引用します。


When we tested the best true wireless earbuds of 2019, we chose AirPods as the best on the market. We were wowed by their impressive audio quality, which was leaps and bounds better than their wired counterparts. We also loved how lightweight they were, how seamlessly they connected to other Apple products, and their ultra-long battery life.
(Isabelle Kagan. Apple AirPods are on sale for Prime Day—and they WILL sell out. USA Today. July 16, 2019.)


この記事の用例では、”leaps and bounds”は形容詞の”better”を強調する意味合いで使われており、急成長やうなぎ登りという意味とはちょっと違っています。

アップル社のAirPodという製品のレビュー記事なのですが、他社製品との比較というコンテクストですので、（製品の性能が）飛躍的に向上している、というような意味合いになると思われます。