hemisphere (n.)youdaoicibaDictYouDict[hemisphere 词源字典]
late 14c., hemysperie, in reference to the celestial sphere, from Latin hemisphaerium, from Greek hemisphairion, from hemi- "half" (see hemi-) + sphaira "sphere" (see sphere). Spelling reformed 16c. Of the Earth, from 1550s; of the brain, 1804.[hemisphere etymology, hemisphere origin, 英语词源]