stratum

Compared meaning: one level of material covering a surface (noun).

比较义项：覆盖或构成表面的一层材料（名词）。

• layer

  General everyday word for a layer of any material; used casually or technically, and commonly paired with verbs like add, peel off, or remove.

  layer 是日常通用词，可以指任何材料的一层，可用于随意或专业语境，常与 add（加）、peel off（剥掉）、remove（去掉）等动词搭配。

  She added another layer of blanket to stay warm at night.

  为了在夜里保暖，她又加了一层毯子。

• stratum 本词

  Formal, technical word almost exclusively used in geology for a distinct layer of rock or soil; plural is strata, and it sounds odd applied to everyday materials.

  stratum 是正式、专业的词，几乎只用于地质学中指岩石或土壤的一层，复数为 strata；用在毯子等日常材料上会显得很奇怪。

  Each stratum of rock revealed a different period of history.

  每一层岩层都揭示了不同的历史时期。

Layer and stratum both mean one level of material. Layer is the everyday word for any material, used casually or technically. Stratum is formal and technical, used mainly in geology for a rock layer, plural strata. Not compared: stratum meaning a social class.

这两个词都表示“层”，但 layer 是日常通用词，可以指任何材料的一层，语域随意；stratum 是较为正式、专业的词，几乎只用于地质学中指岩石的一层，复数为 strata。这里不比较 stratum 表示“阶层”（社会阶层）的比喻义。

Compared meaning: a social class or level in society (noun).

比较义项：阶层（名词）。

• class

  The everyday, common word for a social or economic group, as in 'working class' or 'middle class'; used in both casual speech and formal writing.

  这是表示社会或经济群体的日常常用词，如working class（工人阶级）、middle class（中产阶级）；口语和书面语中都很常见。

  She grew up in a working-class family in a small town.

  她在一个小镇的工人阶级家庭中长大。

• stratum 本词

  A formal, academic word, often used as the plural 'strata', borrowed from geology; it stresses a layered social hierarchy and appears mainly in scholarly or sociological writing, rarely in casual speech.

  这是一个正式、学术化的词，常以复数strata出现，源自地质学；它强调社会等级的分层结构，多见于学术或社会学类的写作，口语中很少使用。

  Economists identify several distinct social strata based on wealth and occupation.

  经济学家根据财富和职业划分出几个不同的社会阶层。

Class and stratum can both mean a social level in society. Class is the everyday word, used in speech and writing, as in working class. Stratum is a formal, academic word, often used in its plural form strata, common in scholarly writing about society.

class 和 stratum 都可以表示社会中的“阶层”，但 class 是日常用语，使用范围更广，口语和书面语都常见；stratum 则更正式、学术化，常以复数 strata 出现，强调社会分层，多见于社会学类的论述。这里不比较 class 的“类别”“班级”等义，也不比较 stratum 的“岩层”义。