It's 2 AM, and you’re tiptoeing past the futon in your shared apartment. Your roommate has been stressed lately, but now, finally, they look at peace. Their chest rises and falls rhythmically. They are asleep.

The word ぐっすり (gussuri) describes this state. It indicates a deep, restful sleep. Someone using this word would be remarking on how completely asleep someone is.

Here are some examples of ぐっすり in action:

The late afternoon sun warms your face as you nap in a park. The breeze gently rustles the leaves overhead. You're stretched out on the grass, utterly relaxed.

Kouen de gussuri nemutte shimatta. (I fell fast asleep in the park.)

You’re at your friend’s apartment after a long night out. The party was fun, but you’re exhausted. You crash on the sofa. Your friend brings a blanket and smiles at you.

Tomodachi no uchi de, gussuri to nemureta. (I was able to sleep soundly at my friend's house.)

Your child is sick with a cold. They've been restless all day, but now they are finally resting. You sit by their bed, relieved that they're finally getting some sleep.

Kodomo wa netsu ga hiita ato, gussuri nemutte ita. (The child was sound asleep after their fever subsided.)

You’re at an all-night study session during the final exam week, and your study group is exhausted. One student had put their head on their desk and, at 3 AM, has finally crashed. Everyone silently cheers for their friend's ability to sleep.

Minna ga tsukarete ite, ichiban tsukarete ita kare wa gussuri to nemurihajimeta. (Everyone was tired, and the most tired of them started fast asleep.)