coaster

coaster /ˈkoʊstɚ/ noun
plural coasters
coaster
/ˈkoʊstɚ/
noun
plural coasters
Britannica Dictionary definition of COASTER
[count]
1 
: a small, flat object on which a glass, cup, or dish is placed to protect the surface of a table
2 
chiefly US : roller coaster 1
3 
: a ship that sails along a coast or that is used in trade between ports of the same country