眼球
がんきゅう · gankyuu · JLPT N1 · noun
eyeball
👁️ 眼球 = 眼 eye + 球 ball, so eyeball (gan-kyuu)
眼 (gan) means eye and 球 (kyuu) means ball or sphere, so the compound is literally eye-ball. The same 球 appears in 地球 (chikyuu, earth-ball) and 野球 (yakyuu, field-ball, baseball).
眼 — eye radical 目 + 艮 (phonetic)
眼 is a semantic-phonetic compound. The left side 目 means 'eye' and gives the meaning, while 艮 on the right supplies the sound. Originally referring to the eyeball, it broadened over time to mean 'eye' generally and, by extension, 'a hole' or 'key point'.
球 — jade radical 玉/王 + qiu 求 (phonetic)
球 is a semantic-phonetic compound. The left side 王 is the 'jade' radical, indicating the original meaning: a fine piece of jade or a jade ornament. The right side 求 supplies the sound 'qiu'. Over time the meaning broadened from a jade sphere to any round object, and today it most commonly means 'ball' or 'globe'.