Why does 人 have a different tone when it's part of the word 大人?

Question

The pinyin for 人 is rén but when it's part of 大人, it's written as dà ren. This is the only word with 人 where that happens (at least in the list of words I went through). Why is there a change in tone?

Answer 1

Google Translate: 人 / rén/ ; 大人 /dàrén/. I don't see the different pinyin for 人

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CantoDict :

人/ren2/

大人 /da4 ren5/2/

(1) adult; grown-up

(2) Your Honour; Your Excellency

(3) [literary] Dear (Father/Mother)

(4) great man; person of high rank or noble mind

Note:

1: Pinyin da4 ren5 is used for first two meanings; da4 ren2 for latter two.

2: "Your Honour" is mainly used on a judge.

In Mandarin:

• 人 on its own is pronounced as /rén/

• When 大人 meant "adult" or "your Honour" 人 is pronounced as /ren/.

• When 大人 meant "Dear" or "great man" 人 pronounced as /rén/

So, you only need to remember 人 pronounces differently as /ren/ only when you mean to say 大人(adult) or 大人 (your Honour). In all other instances 人 is pronounced as /rén/