/chear"ee oh', chear'ee oh"/ , interj., n., pl. cheerios . Chiefly Brit.
interj.
1. good-bye; good-bye and good luck.
2. (used as a toast to one's drinking companions.)
n.
3. a good-bye or farewell.
4. a toast of "cheerio!"
[ 1905-10; see CHEERO; source of -i- is unclear ]