n. An advocate of coalition or a partner in a coalition
adj. Advocating coalition
the GNU version of the Collaborative International Dictionary of English
n. One who joins or promotes a coalition; one who advocates coalition.
The Century Dictionary and Cyclopedia
n. One who favors coalition, or who is a member of a coalition.
Word Usage
"Unfortunately the former pro-coalitionist Lib Dems have gone in the opposite direction, thereby becoming the most useless political party in the Senedd."