sharpen

【原文】
Meanwhile, online stores have further sharpened purchase decisions and prices, leading some shoppers to come into the stores only when they can cherry pick discounted items.

【単語の意味（英語）】
become or make something better, more skilful, more effective, etc = improve
if your voice sharpens or something sharpens it, it become high and loud in an unpleasant way

【単語の意味（日本語）】
～をはっきりさせる；～を向上させる

【コメント】
「はっきりさせる」 define