Example sentences
zhè这xiē些hái孩zi子zhēn真kě可ài爱。
These kids are so cute.
hái孩zi子dōu都ài爱wán玩。
Kids all love to play.
About this word
孩 means "child" and 子 is the same 子 you see in 桌子, 椅子 and 胖子, a noun suffix worn down to a neutral tone. So 孩子 is "child" with a tail on it, not "child child". Chinese does not split son and daughter inside this word: 孩子 covers both, and you add 男 or 女 only when the distinction matters. Parents keep using 孩子 for their grown children, and 这孩子, "this kid", is a common way to talk about someone with a touch of fondness, even an adult.
The story behind the character
孩
孩 is 子 (a child) with 亥 for the sound. Xu Shen's dictionary lists the character under 咳, which he glosses as 小兒笑也, a baby's laugh, and that one is written with 口. Swap the mouth for a child and you get 孩. So the character for child started as the sound of a baby giggling.
子
子 is a newborn drawn from life. Big head, arms stretched out, legs swaddled together. The oldest forms are exactly that, and Xu Shen simply marked it 象形, a picture. It is also the first of the twelve earthly branches, the one paired with the rat, which is why the character shows up on old calendars and in the zodiac.