Learn Hardcore Korean: dongmuri gwiyeowo.

동물 is a noun meaning “animal.”
이 is the subject particle attached to a noun ending in a consonant; it marks 동물 as the subject.
귀여워 is the casual-style present tense form of the adjective 귀엽다 (“to be cute”), functioning here as the predicate: “is cute.”

Why is there no 다 at the end of 귀여워?

The dictionary (citation) form of the adjective is 귀엽다, which ends in 다.
In casual spoken Korean, you drop 다 and adjust the stem for the present tense:
귀엽다 → stem 귀엽-
- casual ending -어 → 귀여워.

How do you make 귀여워 polite?

To speak politely, simply add 요:
귀여워요 (“is cute,” polite).
In even more formal or written styles, you might use the 하십시오-style:
귀엽습니다.

What’s the difference between 동물이 귀여워 and 동물은 귀여워?

동물이 귀여워 uses the subject particle 이, focusing on the subject itself: “It’s the animal that’s cute.”
동물은 귀여워 uses the topic particle 은, making “animals” the topic of a general statement: “As for animals, they’re cute.”
You can make both polite by adding 요 at the end.

How would you ask “Is the animal cute?” in casual and polite speech?

Casual question (rising intonation): 동물이 귀여워?
Polite question: 동물이 귀여워요?
Formal written/question style: 동물이 귀엽습니까?

How do you express “That animal is cute” in Korean?

Add a demonstrative before 동물:

Casual: 그 동물이 귀여워
Polite: 그 동물이 귀여워요

How do you change the sentence to the past tense: “The animal was cute”?

Replace the present tense ending -어 with the past -었어 (casual) or -었어요 (polite):

Casual: 동물이 귀여웠어
Polite: 동물이 귀여웠어요

What’s the difference between 귀여운 동물 and 동물이 귀여워?

귀여운 동물 uses the attributive adjective form 귀여운 (stem 귀엽-
- -은) to modify a noun directly: “cute animal.”
동물이 귀여워 is a full sentence with 동물 as the subject and 귀여워 as the predicate: “The animal is cute.”

Can I say 동물이 귀엽다 instead of 동물이 귀여워?

Yes, 동물이 귀엽다 is the dictionary or citation form, often used in definitions, notes, or when listing words. In everyday conversation, you normally conjugate it to the present tense (동물이 귀여워) or polite form (동물이 귀여워요).