耳 traces the side profile of an ear — the outer pinna and its inner ridges visible in the strokes. Identical across 繁體 / 新字体 / 简体. The character is one of the cleanest pictographs to memorize because the picture has not faded.

耳 builds a small but vivid family of compound characters around hearing. The most beautiful is 聞 (to hear): 門 (gate) + 耳 (ear) — someone leaning at a gate, ear pressed close, listening for sounds outside. The verb is encoded as a scene. Other compounds: 聖 (holy/sage — ear + mouth + standing person, the wise listener), 聴 (to listen attentively), 聲 (voice — the simplified form 声 hides this etymology), 取 (to take — hand grasping ear, recalling an ancient battlefield trophy custom).

Mandarin: ěr, dipping 3rd tone. 耳朵 (ěrduo) is the everyday word for ear; 耳机 (ěrjī) is headphones; 耳环 (ěrhuán) is earrings; 耳鸣 (ěrmíng) is tinnitus. The classical literary 耳 also functioned as a final particle in Classical Chinese ("merely / that is all") — modern readers see this only in citations.

Japanese: on-reading ジ (ji) is rare on its own, mostly in compounds — 耳鼻科 (jibika, ENT clinic). The kun-reading みみ (mimi) is everyday — 耳 (mimi, ear), 早耳 (hayamimi, "fast ear" — someone quick to pick up news), 耳が痛い (mimi ga itai, "my ears hurt" — said when criticism strikes home).

Memory aid: a vertical rectangle with horizontal ridges — outer ear seen from the side. Where 目 rotates a horizontal eye to vertical, 耳 keeps the natural side-view orientation.