悦耳 literally means 'pleasing to the ear' — 悦 (yuè) means 'to delight' or 'to please', and 耳 (ěr) means 'ear'. Together, they form a compound adjective describing sounds that are harmonious, soothing, or melodious — such as music, birdsong, or a gentle voice. It conveys a positive sensory and emotional response, often implying refinement or natural beauty in sound.

This word is commonly used in descriptive, literary, or appreciative contexts — for example, when praising a singer’s voice, describing background music in a café, or commenting on nature sounds. It is more formal and elegant than everyday terms like 好听 (hǎo tīng), and appears frequently in writing, media reviews, and artistic commentary. While it can modify nouns directly (e.g., 悦耳的音乐), it most often follows 是 or functions predicatively (e.g., 这歌声很悦耳).