(1)唯一的，僅有的(without any others of the same type doing the same thing，etc)[作attrib]：He has no brothers or sisters — he's an～child.他沒有兄弟姐妹，是獨(dú)生子。This is the～book of its kind in the world.這是世界上這類書的孤本。He was the～person who came to see me.他是唯一來看我的人?！纪絣one，sole，alone，unique;〖反〗many，several，numerous;
(2)最好(適合的)(so good that there is no other possible choice)(infml)：Running is the～way to keep fit.跑步是保持健康的最好方法。He's the～man for the position.他是擔(dān)任這個(gè)職位的最佳人選。