As defined by the US FDA, a Biologic License Application (BLA) is:

Biological products are approved for marketing under the provisions of the Public Health Service (PHS) Act

Public Health Service Act

The Public Health Service Act is a United States federal law enacted in 1944. The full act is captured under Title 42 of the United States Code "The Public Health and Welfare", Chapter 6A "Public Health Service"....

. The Act requires a firm who manufactures a biologic for sale in interstate commerce to hold a license

License

The verb license or grant licence means to give permission. The noun license or licence refers to that permission as well as to the document recording that permission.A license may be granted by a party to another party as an element of an agreement...

 for the product. A biologics [sic] license application is a submission that contains specific information on the manufacturing processes, chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, pharmacology

Pharmacology

Pharmacology is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function...

, clinical pharmacology

Clinical pharmacology

Clinical pharmacology is the science of drugs and their clinical use. It is underpinned by the basic science of pharmacology, with added focus on the application of pharmacological principles and methods in the real world...

 and the medical affects of the biologic product. If the information provided meets FDA requirements, the application is approved and a license is issued allowing the firm to market the product.

Biologic vs. Biologics vs. Biological

Throughout the FDA web site, literature, and Wikipedia, the following terms have been used:

• Biologic License Application
• Biologics License Application
• Biological License Application
• Biological Product License Application

This article uses the word "biologic" for the following reasons:

1. It is a noun, whereas biological is both an adjective and a noun. Can a license application be "biological"? Not unless it is written on the back of your horse. For clarity, biologic is preferred.
2. "Biological Product" License Application has regulatory weight, as it is used in the Federal Register
   Federal Register
   The Federal Register , abbreviated FR, or sometimes Fed. Reg.) is the official journal of the federal government of the United States that contains most routine publications and public notices of government agencies...
   
   . But as a term, it is seldom used anywhere else.
3. It is singular, and not plural. Since the application is generally for the licensing of one product, the singular form seems to make more sense.
4. It is the term used in the heading of the FDA's glossary entry (although within the entry, it uses "biologics" — see the quoted definition above.)
5. It is the term used on the actual form, which is titled "APPLICATION TO MARKET A NEW DRUG, BIOLOGIC, OR AN ANTIBIOTIC DRUG FOR HUMAN USE"

Note: Upon the creation of this entry, Wikipedia was scoured for use of Biologics License Application and Biological License Application, and these were revised to Biologic License Application; Wiki links to this page were also fixed/added.