antarctic (adj.)youdaoicibaDictYouDict[antarctic 词源字典]
late 14c., antartyk "opposite to the north pole" (adj.), also (with capital A) "region around the South pole" (n.), from Old French antartique, from Medieval Latin antarcticus, from Greek antarktikos "opposite the north," from anti- "opposite" (see anti-) + arktikos "arctic" (see arctic). The first -c- sound ceased to be pronounced in Medieval Latin and was dropped in Old French. Modern English spelling, which restores it, dates from 17c.[antarctic etymology, antarctic origin, 英语词源]
agonic lineyoudaoicibaDictYouDict
"An imaginary line round the earth passing through both the north pole and the north magnetic pole, at any point on which a compass needle points to true north", Mid 19th century: from Greek agōnios, agōnos (from a- 'without' + gonia 'angle') + -ic.