a.

1. 第三的
2. 【醫】第三期的
3. 【化】叔的，特的，三代的
4. （T-）【地】第三紀的

n.

1. （T-）【地】第三紀，第三系
2. 三期梅毒病害
3. 【宗】第三級教士

adj.

1. third in order or level.
   ▸chiefly Brit. relating to or denoting education at a level beyond that provided by schools.
2. relating to or denoting medical treatment provided at a specialist institution.
3. (Tertiary) Geology  relating to or denoting the first period of the Cenozoic era (between the Cretaceous and Quaternary periods, about 65 to 1.64 million years ago).
4. Chemistry  (of an organic compound) having its functional group on a carbon atom bonded to three other carbon atoms.
   ▸Chemistry  derived from ammonia by replacement of three hydrogen atoms by organic groups.

n.