CA
Abbreviation with 8 meanings
| Stands for | California |
|---|---|
| Meanings | 8 |
| Categories | Geography & Places, Science & Engineering, Medical, Education & Academia, Transportation & Travel, Technology & Computing, Law & Legal |
| Also written | Ca |
CA has eight meanings. The most common are California (US state) and Calcium (chemical element); it can also stand for Cancer (carcinoma), Canada, Chartered Accountant, Air China and Certificate authority, plus 1 more listed below.
Meanings of CA at a glance
| # | CA stands for | Context |
|---|---|---|
| 1 | California | Geography & Places › US State |
| 2 | Calcium | Science & Engineering › Chemical Element |
| 3 | Cancer (carcinoma) | Medical › Hematology and Oncology |
| 4 | Canada | Geography & Places › Country Code |
| 5 | Chartered Accountant | Education & Academia › Professional Certification |
| 6 | Air China | Transportation & Travel › Airline Code |
| 7 | Certificate authority | Technology & Computing › Cybersecurity |
| 8 | Confidentiality agreement | Law & Legal › Contract |
1. California
Geography & Places · US State Abbreviations
Most populous US state, with about 39 million residents, admitted on September 9, 1850, as the 31st state shortly after the Gold Rush began. Sacramento is the capital, Los Angeles the largest city, and the Golden State's economy would rank among the world's five largest if it were a country.
Example: Shipping address: 1 Market St, San Francisco, CA 94105, United States.
AP style and most newspapers use Calif.; the shorter Cal. survives in legal citations and older documents. CA was assigned in 1963. In international forms CA is the ISO code for Canada (and the .ca domain), so a five-digit ZIP code points to California while a code like K1A 0B1 points to Canada. CO is Colorado, never California.
2. Calcium (Ca)
Science & Engineering · Chemical Element Abbreviations · also used in medicine
The most abundant metal in the human body, calcium (atomic number 20) stiffens bones and teeth as calcium phosphate and triggers muscle contraction and nerve signaling. As calcium carbonate it forms limestone, marble, chalk and seashells, and heating limestone produces lime for cement, mortar and steelmaking.
Example: Each glass of fortified orange juice provides 350 mg of Ca, about a quarter of the daily value.
Humphry Davy isolated calcium in 1808 by electrolyzing a mixture of lime and mercuric oxide. The name comes from Latin calx (lime), the same root as calculus, which originally meant a small pebble used for counting. Hard water owes its scale-forming habit largely to dissolved calcium and magnesium.
3. Cancer (carcinoma) (Ca)
Medical · Hematology and Oncology Abbreviations
Charting shorthand for cancer or carcinoma, usually combined with the organ involved, as in "breast Ca" or "Ca colon." Carcinoma specifically refers to cancer arising from epithelial cells, the most common type of cancer.
Example: Mother died of ovarian Ca at 52; father with prostate Ca, now in remission.
Because "Ca" also stands for calcium in lab results, writing "CA" or "cancer" in full avoids confusion; "CA" followed by a number names tumor markers such as CA-125. Many patients and clinicians also use euphemisms or abbreviations to avoid the word "cancer" in conversation. Carcinoma differs from sarcoma (connective tissue), lymphoma and leukemia (blood cells) and melanoma (pigment cells).
4. Canada
Geography & Places · Country Code Abbreviations
Two-letter ISO code for Canada, capital Ottawa, alpha-3 CAN. The .ca domain is managed by the Canadian Internet Registration Authority and generally limited to Canadian individuals and organizations.
Example: Select CA for Canada, not California, in the country drop-down.
In US addresses CA means California, the most common source of confusion with this code. In language tags ca is Catalan, so ca-ES means Catalan in Spain, while en-CA and fr-CA are Canadian English and French.
5. Chartered Accountant
Education & Academia · Professional Certification Abbreviations
Accounting designation awarded by professional institutes in countries such as India (ICAI), Scotland (ICAS), Australia and New Zealand (CA ANZ), and historically Canada. In India the CA is among the most respected professional qualifications, earned through a series of demanding exams and articleship training.
Example: After three attempts at the final exams, he became a CA and joined a Big Four firm in Mumbai.
In England and Wales, ICAEW members use ACA (Associate) or FCA (Fellow) instead. Canada merged its CA into the CPA designation in 2014. The Scottish institute, founded in 1854, is often described as the world's oldest professional accountancy body.
6. Air China
Transportation & Travel · Airline Code Abbreviations
Flag carrier of the People's Republic of China, based at Beijing Capital International Airport and a member of Star Alliance. Its logo is a stylized phoenix.
Example: CA 982 from JFK to Beijing arrives at Terminal 3.
ICAO code CCA; callsign "Air China." Formed from the Civil Aviation Administration of China's international division in 1988. Not to be confused with China Airlines (CI) of Taiwan. Air China flies China's head-of-state aircraft.
7. Certificate authority
Technology & Computing · Cybersecurity Abbreviations
An organization or system that verifies identities and issues digital certificates, such as the TLS certificates websites use for HTTPS. Browsers trust a site only if its certificate chains back to a CA in their trusted root store.
Example: Let's Encrypt is a free CA that issues 90-day certificates automatically through the ACME protocol.
Major public CAs include Let's Encrypt, DigiCert, Sectigo and GlobalSign, and companies also run private CAs for internal systems. The CA/Browser Forum sets issuance rules, and browsers can distrust an authority that breaks them, as happened to Symantec's certificate business in 2018. In other contexts CA means California or chartered accountant.
8. Confidentiality agreement
Law & Legal · Contract Abbreviations
Name used especially in mergers and acquisitions and commercial real estate for the agreement a prospective buyer signs before receiving confidential information about a target company or property. It works as an NDA but often adds deal-specific terms such as standstills and non-solicitation of employees.
Example: The investment bank will release the confidential information memorandum once your fund signs the CA.
In public-company M&A, the CA frequently includes a standstill clause barring the bidder from buying shares or launching a hostile offer for a set period, and Delaware courts have enforced such terms. In most other settings, CA abbreviates California or chartered accountant, so context matters.
Related abbreviations
More US state abbreviations
- AK – Alaska
- AL – Alabama
- AR – Arkansas
- AZ – Arizona
- CO – Colorado
- CT – Connecticut
- DC – District of Columbia
- DE – Delaware
See all 51 US state abbreviations →
More chemical element abbreviations
- Bi – Bismuth
- Bk – Berkelium
- Br – Bromine
- C – Carbon
- Cd – Cadmium
- Ce – Cerium
- Cf – Californium
- Cl – Chlorine
See all 118 chemical element abbreviations →
This entry is for general education and is not medical or legal advice. Abbreviation use varies between institutions; always confirm in context.