(countable, biochemistry, immunology) Initialism of acute-phase protein. / (countable, biochemistry, medicine) Initialism of amyloid precursor protein.

(law) Abbreviation of appendix. (text added to the end of a book or an article) / Abbreviation of apprentice.

(law) Abbreviation of appendices.

plural of APP

(informal, computing) A killer application.

(law) Abbreviation of court of appeals.

plural of killer app

(law) Abbreviation of United States Court of Appeals for Veterans Claims, as used in case citations.

A web application.

plural of web app