topline

/T AA1 P L AY0 N/
noun
  1. 1

    The upper curvature of a horse's or dog's withers, back, and loin.

  2. 2

    Principal billing.

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).

Source: https://en.wiktionary.org/wiki/topline