累 (lèi) means “tired” | MotiTan Chinese Dictionary

More examples

我现在很累。wǒ xiàn zài hěn lèi

I am very tired now.

Movement and attention becoming heavy under a growing load of effort.

困kùn: Being sleepy, unfocused, and unable to keep the eyes open easily.

因长时间的活动或事务累积而产生的疲倦感。yīn cháng shí jiān de huó dòng huò shì wù lěi jī ér chǎn shēng de pí juàn gǎn

累 (lèi, "tired") is connected with the lěi reading meaning "to pile up," which helps link the word with fatigue that builds over time.

Chinese uses this adjective for both physical and mental fatigue, so it fits after sports, homework, travel, or a long day.