single

Compared meaning: not married (adjective).

比较义项：未婚，没有配偶（形容词）。

• single 本词

  Common, everyday word for not being married; can also simply mean not currently in a romantic relationship, and is used freely in casual conversation.

  常见的日常用词，表示未婚；也可以单纯指没有恋爱对象，常用于日常口语交流中。

  My brother is thirty-five and still single, though he says he's happy that way.

  我哥哥三十五岁了还是单身，不过他说他这样很开心。

• unmarried

  Formal, literal term used mainly in official, legal or written contexts to state marital status precisely, without implying anything about dating or relationships.

  较为正式、字面化的用词，主要用于官方、法律或书面语境，客观说明婚姻状态，不涉及恋爱关系。

  The form asks whether you are married or unmarried before listing your dependents.

  表格要求先说明你是已婚还是未婚，然后再填写受抚养人信息。

Single and unmarried both mean not married. Single is common and casual, and can also simply mean not in a romantic relationship. Unmarried is formal, used mainly in official or written contexts to state marital status plainly, without suggesting anything about dating.

这两个词在“未婚”这个意义上很接近，但语体和用法不同：single是日常口语用词，也可以泛指没有恋爱对象；unmarried更正式，多用于官方或书面语境，只客观说明婚姻状况。这里不比较single的“单一的、一个的”等其他意义。

Compared meaning: being the only one of its kind (adjective).

比较义项：形容“只有一个”或“独自存在”的状态（形容词）。

• lone

  Lone describes someone or something standing apart, alone in a scene; it is mainly literary, used before a noun, and stresses solitariness rather than being the only one of a kind.

  lone用来描写某人或某物在场景中显得孤零零、独自一个，通常放在名词前，语气偏文学化，强调的是孤单感，而不是“同类中唯一的一个”。

  A lone wolf howled somewhere in the dark forest.

  一只孤狼在黑暗的森林中某处嚎叫。

• only

  Only means no other person or thing fits that role here; it usually follows 'the' and stresses that all others are excluded, not that something stands physically apart.

  only表示在这个场合里没有其他人或物符合这个角色，通常与“the”连用，强调把其他一切都排除在外，而不是强调身体上的孤立。

  She was the only witness who saw the accident happen.

  她是唯一目睹事故发生的目击者。

• unique

  Unique stresses that nothing else is exactly like it; it describes a special or distinctive quality, not physical solitude or exclusivity among a group.

  unique强调没有任何其他事物与它完全相同，描述的是一种特别或与众不同的特质，而不是身体上的孤单或在同类中的排他性。

  This restaurant's fusion menu gives it a truly unique dining experience.

  这家餐厅的融合菜单让它拥有真正独一无二的用餐体验。

• single 本词

  Single simply counts one item as opposed to more than one; it highlights quantity, not exclusivity or distinctiveness, and pairs naturally with countable nouns.

  single只是单纯地表示数量上“只有一个”而不是更多，强调的是数量，而不是排他性或独特性，常与可数名词搭配。

  The whole trip was cancelled because of a single mistake.

  整趟旅程因为一个单一的失误而被取消。

Lone, only, unique, and single all relate to being one. Lone describes someone or something standing alone. Only means no other person or thing fits that role, stressing exclusion. Unique stresses a special quality nothing else has. Single simply counts one item, not exclusivity.

这四个词都表示“仅此一个”的概念，但强调点不同：lone侧重孤零零、视觉上的孤单，语气偏文学化；only强调排他性，即“再没有别的”；unique强调独一无二、无可比拟的特质；single纯粹指数量上“只有一个”，语气中性。注意：single在其他语境中还有“单身的”之义，only也可作副词“仅仅”，这两个义项这里都不涉及。

Compared meaning: the number one (noun).

比较义项：数量“一”（n.）。

• one

  The plain cardinal number for the quantity 1; a neutral pronoun or determiner, the everyday way to state a count with no extra emphasis.

  基础基数词“1”；用作中性的代词或限定词，是表达数量时最普通、不带强调意味的说法。

  She has one brother and two sisters in her family.

  她家里有一个哥哥和两个姐妹。

• single 本词

  Emphasizes that there is only one and no more, often stressing smallness or limitation; usually a determiner before a noun, rarely standing alone as a pronoun.

  强调“只有一个，不多”，常带有渺小或受限的意味；通常放在名词前作限定词，很少单独作代词使用。

  He lived alone in a single small room for years.

  他多年来独自住在一间狭小的房间里。

One and single both can mean the number one. One is the plain cardinal number, used as a pronoun or before a noun. Single stresses there is only one, usually before a noun, rarely alone. Single also means 'not married' or 'one-way'; not compared here.

这两个词都能表示“一”，容易混用：one 是最普通的基数词，可直接作代词或修饰名词，不带强调意味；single 则强调“只有一个，不多不少”，常用于 “a single + 名词” 的结构，语气更正式、更突出数量之少。这里不比较 single 表示“单身的”“单程的”等其他义项。