plainer; plainest
1
: having no pattern or decoration
Her dress was plain.
a plain fabric
It was a plain room with no curtains.
She was wearing plain black shoes.
He printed the picture on plain paper.
2
: not having any added or extra things
a glass of plain [=pure] water
a piece of plain chicken
plain yogurt
You don't have to call me Mr. Johnson—just plain Fred will be fine.
(Brit) The recipe calls for 250 grams of plain flour. [=(US) all-purpose flour]
3
: easy to see or understand
It's plain to see [=it's obvious] that you don't like dogs.
You should have made it plain [=clear] to us what you were planning to do.
What he said is a lie, plain and simple.
The evidence makes it plain [=clearly shows] that he is guilty.
The answer is (as) plain as day. = The answer is as plain as the nose on your face. [=the answer is very obvious]
4
: simple and honest
The senator was known for his plain speaking.
Let me say it in plain English: you're fired.
5
always used before a noun
: complete and total
His motive was plain [=pure, sheer] greed.
The lawyer stated the plain facts of the case.
Her story is the plain truth.
6
: not unusual or special in any way : ordinary
We're just plain, hardworking people.
plain common sense
(US) I'm just a plain old country boy.
(US) All kinds of people attended the event, including politicians, celebrities, and just plain folks. [=ordinary people]
7
: not handsome or beautiful
She's really kind of plain.
She describes herself as a plain Jane. [=a woman who is ordinary looking and not beautiful or glamorous]
plural plains
: a large area of flat land without trees
the Spanish plain
the Great Plains of the United States
informal
: truly or completely
Her answer was misleading, if not plain dishonest.
—used to make a statement or description more forcefulShe plain forgot to call me.
You are just plain wrong.
Cite this Entry
“Plain.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/plain. Accessed 20 Jun. 2026.
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