apsis
apsis[ˈapsɪs](pl. apsides -diːz)- either of two points on the orbit of a planet or satellite that are nearest to or furthest from the body round which it moves
拱(极)点
派生apsidaladjective语源- early 17th cent. (denoting the orbit of a planet): via Latin from Greek apsis, hapsis 'arch, vault', perhaps from haptein 'fasten, join'
考试词汇表