[cheer-ee-oh, cheer-ee-oh] 
interjection, noun, plural cheer⋅i⋅os. Chiefly British| 1. | good-bye; good-bye and good luck. |
| 2. | (used as a toast to one's drinking companions.) |
| 3. | a good-bye or farewell. |
| 4. | a toast of “cheerio!” |
| cheer·i·o (chîr'ē-ō') interj. Chiefly British Used in greeting or parting. [Alteration of cheer.] |
iˌoʊ