Build a relationship chain and get the correct Chinese kinship term. The five words for "uncle", the 堂/表 cousin split, and where Hong Kong differs.

Why Chinese needs this and English does not

English has about twenty kinship words and reuses them freely. Uncle covers five distinct people. Chinese has a separate word for nearly every position, and the position is fixed by four things at once:

Which side — paternal or maternal. 爺爺 against 外公, 姪子 against 外甥.
Generation — one step up or down and the word changes entirely.
Relative age within a generation — 伯父 and 叔叔 differ only in whether he is older or younger than your father.
Blood or marriage — 姑姑 against 姑丈, 姊姊 against 嫂嫂.

Four dimensions multiplied together is a table nobody memorises, which is why getting it wrong at a family gathering is an annual tradition.

The five uncles

Term	Who	Why that word
伯父 bófù	Father’s elder brother	paternal blood, older than father
叔叔 shūshu	Father’s younger brother	paternal blood, younger than father
舅舅 jiùjiu	Mother’s brother	maternal blood, age irrelevant
姑丈 gūzhàng	Husband of father’s sister	paternal, by marriage
姨丈 yízhàng	Husband of mother’s sister	maternal, by marriage

Note the asymmetry: the father’s brothers split by age, and the mother’s brothers do not. That is not an oversight. It is a fossil of the patrilineal clan system, where seniority on the father’s side determined inheritance and ritual precedence, and seniority on the mother’s side determined nothing.

堂 and 表 are not “paternal” and “maternal”

This is the rule most often stated wrongly, including in most English explanations.

The actual rule: only the children of your father’s brothers are 堂. Everyone else is 表.

Relationship	Term
Father’s elder brother’s son	堂哥／堂弟
Father’s younger brother’s daughter	堂姊／堂妹
Father’s sister’s son	表哥／表弟
Mother’s brother’s son	表哥／表弟
Mother’s sister’s daughter	表姊／表妹

Your father’s sister’s child is on the paternal side and is still 表. The reason is that 堂 means the same ancestral hall — people who share your surname and worship at the same shrine. An aunt married out, and her children take their father’s surname, so they are outside the clan and therefore 表.

The same logic explains nephews and nieces: a brother’s children are 姪, a sister’s are 甥. The split follows the sex of the connecting sibling, not the sex of the child.

Taiwan and Hong Kong differ

Both write Traditional Chinese, and their everyday terms are not identical. The grandparents are where it shows:

Relationship	Taiwan	Hong Kong
Father’s father	爺爺	爺爺
Father’s mother	奶奶	嫲嫲
Mother’s father	外公	公公
Mother’s mother	外婆	婆婆

The last two are a genuine trap. In Hong Kong 公公 and 婆婆 are your maternal grandparents; in Taiwan the same two words mean your husband’s parents. Same characters, different people, and it is the pair most likely to cause a real misunderstanding.

The tool shows both wherever they diverge.

Two sets of in-laws

Which words you use for a spouse’s parents depends on which spouse you are:

You are the	Their father	Their mother
Wife	公公	婆婆
Husband	岳父	岳母

Siblings’ spouses have their own terms, and these keep the age distinction: an elder brother’s wife is 嫂嫂, a younger brother’s wife is 弟妹, an elder sister’s husband is 姊夫, a younger sister’s husband is 妹夫.

Some relationships have no age

The tool sometimes answers with two words — 堂哥／堂弟, for instance. That is not vagueness; the information is genuinely not in the chain.

You can say “my elder brother” because you know he is older. “My uncle’s son” tells nobody whether he is older or younger than you, and the correct term depends on his age against yours, not on his father’s age against your father’s.

The same applies to “my father’s son”: that is your own brother, but the chain has not said which kind.

What this covers

Up to great-grandparents, down to grandchildren, and across to cousins, nephews, nieces and in-laws — roughly three generations. Beyond that it says so rather than guessing.

A wrong kinship term is worse than no term, so buttons that lead nowhere are greyed out rather than removed. Which ones are unavailable is itself informative: it shows where the table stops.

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Chinese family titles