plain

Compared meaning: not complicated or decorated (adjective).

比较义项：朴素的，简单的，不复杂或不加修饰的（形容词）。

• simple

  Simple stresses that something is easy to understand or not complicated in structure or process, e.g. simple instructions, a simple design, a simple task.

  simple强调事物容易理解，结构或过程不复杂，例如简单的说明、简单的设计、简单的任务。

  The instructions were simple enough for anyone to follow.

  这些说明非常简单，任何人都能看懂照做。

• plain 本词

  Plain stresses a lack of decoration or extra features - unadorned, ordinary, without embellishment - often describing food, clothing or style rather than difficulty.

  plain强调不加装饰、没有多余的花样——朴素、普通、未经修饰，常用来形容食物、穿着或风格，而不是难易程度。

  He prefers plain rice without any sauce or spices on top.

  他更喜欢不加任何酱汁或香料的清淡米饭。

Both can mean 'simple, not complicated'. Simple stresses that something is easy to understand, as in simple instructions or a simple task. Plain stresses a lack of decoration, often describing food, clothing, or style. Not covered: plain meaning 'clear', as in a plain statement.

这两个词在“不复杂、朴素”这一意义上很接近，容易混淆：simple强调事物本身容易理解、操作或结构不复杂；plain强调外观上不加装饰、朴素普通，常用于食物、穿着、说话方式等。这里不比较plain的“清楚的”这一义项（如make one's meaning plain，意为把话说清楚）。

Compared meaning: simple in style, not decorated (adjective).

比较义项：风格简洁、不复杂／朴素无装饰（形容词）。

• clean

  Clean describes a style, design or piece of writing that is neat, uncluttered and easy to follow; it usually sounds like praise, as in "clean lines" or "clean prose."

  Clean 用来形容风格、设计或文字简洁明快、条理清楚，通常带有褒义，例如“简洁的线条”或“简洁的文笔”。

  The architect designed a clean, minimalist facade with none of the usual clutter.

  这位建筑师设计了简洁的极简主义外墙，没有任何多余的装饰。

• plain 本词

  Plain describes something with no decoration, pattern or extra features; it can sound neutral or slightly negative, as in "plain food" or "a plain dress."

  Plain 用来形容没有装饰、图案或额外元素的事物，语气可能中性甚至略带贬义，例如“朴素的食物”或“朴素的裙子”。

  The old farmhouse had plain wooden furniture with no carvings or paint.

  这栋老农舍里摆着朴素的木制家具，没有雕花也没有上漆。

Clean and plain both describe a simple style. Clean usually sounds like praise, meaning neat and well-organized, as in 'clean lines'. Plain is more neutral, meaning with no decoration, as in 'plain food'. This does not compare clean as 'not dirty', or plain as 'clear'.

这两个词在“风格简单、不繁复”这层意思上很接近，但语气不同：clean 通常带有褒义，强调条理清楚、干净利落；plain 语气更中性甚至略带贬义，强调朴素或缺少装饰。这里不比较 clean 表示“干净的”（如打扫房间）的意思，也不比较 plain 表示“清楚明白的”的意思。