ABCD

ABCD is a list of the first four letters in the English alphabet. It may also refer to:

In medicine

• ABC (medicine), also known as ABCD, a mnemonic for steps in resuscitation
• ABCD rating, a staging system for prostate cancer
• ABCD syndrome, a genetic disorder
• ABCD guideline, a heuristic for detecting melanomas
• ABCD² score, a score for determining the risk of stroke after TIA

In science

• ABCD matrix analysis, a type of ray tracing technique used in the design of some optical systems
• ABCD-parameters, a type of properties describing the electrical behavior of linear electrical networks
• ABCD Schema, a highly-structured data exchange and access model for taxon occurrence data (specimens, observations, etc. of living organisms), i.e. primary biodiversity data

In other fields

• Action for Boston Community Development, Inc. (ABCD), a Boston, Massachsuetts based non-profit social services agency
• CompTIA, also known as the Association of Better Computer Dealers
• ABCD Region, an industrial district outside of São Paulo, Brazil
• American-Born Confused Desi, refers to American youth of South Asian descent
  • ABCD (2005 film), a Tamil-language Indian film
• Asset-based community development, a methodology that seeks to uncover and highlight the strengths within communities
• USS Atlanta (1884), USS Boston (1884), USS Chicago (1885), and USS Dolphin (PG-24), the first four steel ships built during the "New Navy" period of U.S. Naval history
• ABCD: add, browse, change, delete, another representation of Create, read, update and delete
• American, British, Chinese, and Dutch, the main powers opposing the Empire of Japan before the Pacific War in World War II
• Archer Daniels Midland, Bunge, Cargill, and Louis Dreyfus, four major agriculture commodity companies
• ABCD (film), a 2005 film