飲み込む
のみこむ · nomikomu · JLPT N1 · verb-godan
to understand
🥤 飲 (nomu, drink) + 込む (komu, go into): drink it all the way in, so to gulp down or swallow deeply
Used figuratively for taking in or understanding something fully: the drink goes deep, the idea goes deep. 飲み込みが早い means quick to grasp.