topline

Short definition from Wiktionary

Noun

1. 1
   The upper curvature of a horse's or dog's withers, back, and loin.
2. 2
   Top billing.
3. 3
   The edge that runs along the top of the opening of a shoe.
4. 4
   The vocal parts of a piece of music (particularly pop).

Verb

1. 1
   To bill (a performer) as the primary entertainer in a production.
2. 2
   To be billed as the primary entertainer in (a production).
3. 3
   (music) To compose and/or sing the vocal part of a song (particularly pop).