(literary or bound form) diligent; hardworking; industrious (as in 孜孜不倦 zī​zī​bù​juàn)

(literary) without stop; ceaselessly; also used to describe laughing continuously

(literary) carefully; attentively; specifically when watching or staring at something

(literary) gentle and soft in manner; sweet; submissive

(literary) sound of birds chirping; twittering

(bound form) used after certain adjectives like 喜 xǐ to describe a happy or joyful appearance