adjective

1. Obsolete flat; level; plane
2. free from obstructions; open; clear in plain view
3. clearly understood; evident; obvious to make one's meaning plain
4. 1. outspoken; frank; straightforward plain talk
   2. downright; thoroughgoing plain nonsense
5. not luxurious or ornate; unembellished a plain coat
6. not complicated; simple plain sewing
7. not good-looking; homely a plain face
8. not figured, dyed, or twilled plain cloth
9. pure; unmixed plain soda
10. not of high rank or position; such as characterizes the common people; ordinary a plain man

Etymology: OFr < L planus, flat, level < IE base *plā-, broad, flat > floor, field

noun

adverb

intransitive verb

Etymology: ME pleynen < OFr plaindre < L plangere: see plaint