not decorated or elaborate; simple or basic in character

good plain food

everyone dined at a plain wooden table

having no pretensions; not remarkable or special

a plain, honest man with no nonsense about him

easy to perceive or understand; clear

the advantages were plain to see

it was plain that something was wrong

(of a person) not beautiful or attractive (typically used of a woman)

a plain, round-faced woman

sheer; simple (used for emphasis)

the main problem is just plain exhaustion

denoting or relating to a type of knitting stitch produced by putting the needle through the front of each stitch from left to right

used for emphasis

perhaps the youth was just plain stupid

clearly or unequivocally

I'm finished with you, I'll tell you plain

a large area of flat land with few trees

the coastal plain

mourn or lament