1
- not decorated or elaborate; simple or ordinary in character无装饰的, 简易的, 不复杂的; 素净的, 清淡的, 朴素的, 简朴的：
good plain food
美味而清淡的食品
everyone dined at a plain wooden table.
大家都在一张简易木桌上吃饭。
1.1
- without a pattern; in only one colour平纹的; 单色的, 素色的：
a plain fabric.
平纹织物。
1.2
- bearing no indication as to contents or affiliation空白的：
donations can be put in a plain envelope.
可以把捐款放进一个空白信封中。
1.3
- (of paper) without lines（纸）无行线的。
1.4
- (of a person) having no pretensions; not remarkable or special（人）朴实的; 普通的, 平凡的：
a plain, honest man with no nonsense about him.
一个朴实诚恳不轻浮的人。
1.5
- attrib.(of a person) without a special title or status（人）无头衔的, 无身份的：
for years he was just plain Bill.
多年来, 比尔不过是个平头老百姓。
2
- easy to perceive or understand; clear明显的, 明白的; 清晰的, 清楚的：
the advantages were plain to see
优势显而易见
it was plain that something was very wrong.
很显然有地方出大错了。
2.1
- attrib.(of written or spoken usage) clearly expressed, without the use of technical or abstruse terms（书面或口头用法）表达清楚的, 清新的; 不用技术词汇或深奥词汇的：
written in plain English.
用简明英语写成的。
2.2
- not using concealment or deception; frank无遮拦的, 真诚的; 直截了当的, 坦率的：
he recalled her plain speaking.
他回忆起她坦诚的话语。
3
- (of a woman or girl) not beautiful or attractive（妇女, 少女）不漂亮的, 不迷人的：
the dark-haired, rather plain woman.
长相很一般的黑发女人。
4
- attrib. sheer; simple (used for emphasis)［用于强调］纯粹的, 完全的：
the main problem is just plain exhaustion.
主要问题就是太疲倦了。
5
- (of a knitting stitch) made by putting the needle through the front of the stitch from left to right（针法）平针的。比较PURL1.
informal <非正式>
1
- as submodifier used for emphasis［用于强调］就是, 完全地：
perhaps the youth was just plain stupid.
或许那位青年不过是太笨了而已。
2
- clearly; unequivocally明白地; 不含糊地：
I'm finished with you, I'll tell you plain.
我们俩一刀两断了, 明白告诉你。
- a large area of flat land with few trees平原。
短语
as plain as the nose on one's face
- informal very obvious〈非正式〉非常明显, 明明白白。
plain and simple
- informal used to emphasize the statement preceding or following〈非正式〉［用于强调前面或后面的观点］当然, 显然。
plain as day
- informal very clearly〈非正式〉非常明显, 明明白白。
派生词
plainness
noun词源
Middle English: from Old French plain, from Latin planus, from a base meaning 'flat'.