Placental is mainly the adjective of placenta: relating to the placenta, or having one. Doctors use it for problems and features of that organ — placental blood, placental tissue, and conditions like placental abruption, where the placenta comes away from the wall of the womb too early.

Placental is mainly the adjective of placentaplacental主要是placenta(胎盤)的形容詞 relating to the placenta, or having one意思是跟胎盤有關，或是有胎盤 Doctors use it for problems and features of that organ醫生會用它來講這個器官的問題和特徵 placental blood, placental tissue像是placental blood(胎盤血)、placental tissue(胎盤組織) and conditions like placental abruption還有像placental abruption(胎盤早期剝離)這樣的狀況 where the placenta comes away from the wall of the womb too early也就是胎盤太早從子宮壁剝離

The second use is in biology, and it is the one most learners meet first. Placental mammals are the huge group of mammals whose babies grow inside the mother, fed by a placenta, until they are fairly developed — humans, dogs, whales, elephants, mice.

The second use is in biology第二種用法是在生物學裡 and it is the one most learners meet first也是大多數學習者最先遇到的 Placental mammals are the huge group of mammalsplacental mammals(有胎盤哺乳動物)是龐大的一群哺乳動物 whose babies grow inside the mother牠們的寶寶在母體內發育 fed by a placenta靠胎盤提供養分 until they are fairly developed直到相當成熟才出生 humans, dogs, whales, elephants, mice像人類、狗、鯨魚、大象、老鼠

They are set against marsupials like kangaroos, whose babies are born tiny and finish growing in a pouch, and against the odd egg-laying mammals like the platypus.

They are set against marsupials like kangaroos牠們和kangaroos(袋鼠)這類有袋動物形成對比 whose babies are born tiny and finish growing in a pouch有袋動物的寶寶出生時很小，要在育兒袋裡繼續發育 and against the odd egg-laying mammals like the platypus也和platypus(鴨嘴獸)這種特別的產卵哺乳動物不同

In that biology sense the word can also be a noun: 'a placental' simply means a placental mammal, and you will see 'the placentals' in textbooks. That noun use is quite technical and you never need to produce it yourself — but recognising it saves confusion when you meet it.

In that biology sense the word can also be a noun在生物學的這個意義裡，這個字也可以當名詞 'a placental' simply means a placental mammal「a placental」就是指一隻胎盤哺乳動物 and you will see 'the placentals' in textbooks教科書裡也會看到「the placentals」這樣的說法 That noun use is quite technical這種名詞用法相當專業 and you never need to produce it yourself你自己不需要主動用它 but recognising it saves confusion when you meet it但看到時能認出來就不會困惑

The word is neutral and scientific; it has no everyday emotional colour at all.

The word is neutral and scientific這個字中性、很科學 it has no everyday emotional colour at all完全沒有日常生活裡的情感色彩