(~s)
1.
Number one means better, more important, or more popular than anything else of its kind. (INFORMAL)
The economy is the ~ issue by far...
By the way, I’m your number-one fan.
ADJ: ADJ n
2.
In popular music, the ~ is the best selling CD in any one week, or the group or person who has made that CD. (INFORMAL)
Paula is the only artist to achieve four ~s from a debut album.
N-COUNT