- Free from obstructions; open; clear: in plain view. (adjective)
- Obvious to the mind; evident: make one's intention plain. See Synonyms at apparent. (adjective)
- Not elaborate or complicated; simple: plain food. (adjective)
- Straightforward; frank or candid: plain talk. (adjective)
- Not mixed with other substances; pure: plain water. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.