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