from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A member of an opposition.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A person who opposes; especially a member of an official opposition
from the GNU version of the Collaborative International Dictionary of English
- n. One who belongs to the opposition party.
from The Century Dictionary and Cyclopedia
- n. One of the opposition; one who belongs to the party opposing the existing administration or the party in power.
opposition + -ist (Wiktionary)