A pachyderm is a large animal with very thick skin. The word was made for animals such as the elephant, and people also use it for the rhinoceros and the hippopotamus. In ordinary English it is a slightly bookish way of talking about those animals, especially elephants.

A pachyderm厚皮動物 is a large animal with very thick skin是一種皮膚很厚的大型動物 The word這個字 was made for animals such as the elephant是為了像大象這樣的動物造的 and people also use it for the rhinoceros and the hippopotamus也用在犀牛和河馬身上 In ordinary English在一般英文裡 it is a slightly bookish way of talking about those animals是談論這些動物時稍微書面一點的說法 especially elephants尤其是大象

Though actually, scientists do not really group those animals together any more: an elephant, a rhino, and a hippo are not close family in modern biology. The old label stayed in the language because the thick skin is what you notice.

Though actually不過實際上 scientists do not really group those animals together any more科學家其實已經不太把這些動物歸在一起了 an elephant, a rhino, and a hippo大象、犀牛、和河馬 are not close family in modern biology在現代生物學裡並不是近親 The old label這個舊標籤 stayed in the language之所以留在語言裡 because the thick skin is what you notice是因為厚皮是最讓人注意到的地方

You may also hear it, a little jokingly, for a person who does not seem to feel criticism — as if they had thick skin too. That is a stretch of the animal meaning, not a separate technical sense.

You你 may also hear it, a little jokingly, for a person who does not seem to feel criticism也可能聽到有人半開玩笑地拿它形容一個好像不會在意批評的人 — as if they had thick skin too彷彿他們也有厚皮 That這 is a stretch of the animal meaning是動物義的延伸用法 not a separate technical sense不是另一個獨立的專業意義