topline

noun

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

   “When viewing the horse in profile, attention must be paid to the curvature and proportions of the topline.”

2. (attributive, often)Top billing.

   “In recent weeks Cosby has, perhaps more than any other topline entertainer of the moment, been both at the pinnacle and at the crossroads.”

3. (attributive, often)The first line, the topmost-ranking line; the most important thing.

   “Near-synonyms: (in attributive uses) TLDR, BLUF, bottom-line, bottom line”

   “topline takeaways”

4. The edge that runs along the top of the opening of a shoe.
5. The vocal parts of a piece of music (particularly pop).

verb

1. (transitive)To bill (a performer) as the primary entertainer in a production.

   “A popular series of musical shorts he made for Mack Sennett's company in 1930 added to his success as a radio vocalist, and had made him a star by the end of 1931, when Paramount toplined him in The Big Broadcast […]”

2. (ambitransitive)To be billed as the primary entertainer in (a production).

   “[Whitney] Houston's success in music led her to topline the features "Waiting to Exhale," "The Preacher's Wife" and the telefilm "Cinderella."”

   “Although occasionally he toplined in a “B” picture, he found his greatest achievements were as a character actor.”

   “Over the next few years he toplined three "Encores!" productions […]”

3. (transitive)(music) To compose and/or sing the vocal part of a song (particularly pop).