1A child or young person who has not yet reached adulthood; a general term for kids, teens, and youths.
公園で子が元気に走り回っている。
Children are running around energetically in the park.
その学校は3歳から入学できる小さな子を受け入れている。
That school accepts young children starting from age three.
最近の子はデジタル機器の扱いに慣れている。
Kids these days are used to handling digital devices.
あの子はまだ中学生だが、しっかりしている。
That kid is still a junior high student, but very mature.
2One's own son or daughter, from a parent's point of view; one's offspring.
彼女には子が三人いる。
She has three children.
子の将来を考えて貯金を始めた。
I started saving money with my child's future in mind.
親が年を取れば、子が世話をすることも多い。
When parents get older, it's often their children who take care of them.
3A colloquial way to refer to a young woman; casual and slightly informal in tone.
あの店には可愛い子が働いている。
There's a cute girl working at that shop.
若い子たちの間でこの曲が流行っている。
This song is popular among young women.
合コンで隣の席になった子と連絡先を交換した。
I exchanged contact info with the girl who sat next to me at the group date.
4Used before or after an animal name to mean its young (e.g. 子犬 puppy, 子猫 kitten).
生まれたばかりの子猫は目もまだ開いていない。
The newborn kitten hasn't even opened its eyes yet.
近所の犬が子を5匹産んだ。
The neighbor's dog gave birth to five puppies.
池のそばで鳥の子が鳴いている。
A baby bird is chirping near the pond.
5A branch or offshoot derived from something original; used e.g. in 子会社 (subsidiary company) as opposed to a parent company.
この会社は海外に多くの子会社を持っている。
This company has many subsidiaries overseas.
親会社の方針は子にもそのまま適用される。
The parent company's policy is applied to its subsidiaries as well.
6Used in the set phrase 元も子もない ("to lose both principal and interest," i.e. to end up with nothing); here 子 refers to the interest or profit on capital.
そんな無理をして倒れたら、元も子もない。
If you push yourself that hard and collapse, you'll lose everything.
7In finance, a shortened way of saying 子株 (new share); a specialized term for newly issued stock.
増資に伴い、子の割り当てが株主に通知された。
Following the capital increase, shareholders were notified of the allocation of new shares.
8In mahjong and card games, refers to a player who is not the dealer (親).
次の局は私が子になる番だ。
In the next round, it's my turn to be the non-dealer.
9An old term for a young geisha or courtesan; almost never used today, appearing only in historical contexts.
江戸時代の花街には多くの子がいたと伝えられている。
It is said that many young geisha lived in the pleasure quarters of the Edo period.
10An archaic usage referring to the egg of a bird or fish; barely used in modern Japanese.
古典文学には、鳥の子（卵）を採る場面が描かれている。
Classical literature depicts scenes of gathering bird eggs ("ko").
11A suffix attached to a noun or the -masu stem of a verb, meaning "a person who does ~"; often used for young women (e.g. 踊り子 dancer, 売り子 salesgirl).
デパートの売り子が丁寧に商品を説明してくれた。
The salesgirl at the department store carefully explained the product to me.
祭りの屋台で働く踊り子を見かけた。
I saw a dancer working at a festival stall.