ra
ra — adjective
- rapositive
- raercomparative
- raestsuperlative
1. a short form used in medical records, meaning the radial artery — the blood vess
a short form used in medical records, meaning the radial artery — the blood vessel that travels along the inner side of the forearm and supplies blood to the hand and wrist
The surgeon checked the patient's RA before inserting the catheter.
RA = radial artery on medical charts
Nurse Karim recorded the RA pulse at 72 beats per minute.
Blood flow through the left RA appeared normal on the ultrasound.
The doctor noted swelling near the RA and ordered a Doppler test.
用法筆記
Almost always written in capital letters (RA) on medical records or surgical notes.
ra — noun
- rasingular
- rasplural
1. an abbreviation used in cardiology to mean the right atrium — the chamber on the
an abbreviation used in cardiology to mean the right atrium — the chamber on the upper-right side of the heart that collects blood low in oxygen and passes it to the lower chamber below
The echocardiogram showed an enlarged RA in the elderly patient.
RA = right atrium on cardiology reports
Blood enters the RA through the superior and inferior vena cava.
Dr. Yuki measured the pressure inside the RA using a thin tube.
The surgeon repaired a small tear in the wall of the RA.
用法筆記
In medical writing, RA is typically capitalised. Context (cardiology reports, surgery notes) distinguishes it from RA meaning rheumatoid arthritis.
ra — abbreviation
1. short for range — used in mathematics and statistics to mean the difference betw
short for range — used in mathematics and statistics to mean the difference between the largest and smallest numbers in a set
The teacher asked the class to calculate the RA of the data set: 4, 9, 15, 22.
RA = range in statistics
An RA of 18 means the test scores vary widely from 62 to 80.
Diego calculated the RA of the temperature readings for each month.
A small RA suggests the numbers are clustered close together.
The spreadsheet formula returned an RA value of 34 for the sample.
用法筆記
Usually appears in textbooks, spreadsheets, or exam questions. The full word 'range' is far more common in spoken English.
2. short for regular army — the permanent, full-time professional army of a country
short for regular army — the permanent, full-time professional army of a country, as opposed to reserve or volunteer forces
Sergeant Kwame served twelve years in the RA before transferring to the reserves.
RA = regular army, contrasted with reserves
RA units received new equipment before the reserve battalions.
Major Maeve was promoted after fifteen years of RA service.
The treaty limited the size of the country's RA to 50,000 soldiers.
用法筆記
Found mostly in military documents, historical texts, and government reports. In everyday conversation, 'regular army' or 'the army' is used instead.
3. short for research assistant — a person employed to help with academic or scient
short for research assistant — a person employed to help with academic or scientific research, often a graduate student
Mira worked as an RA in the chemistry lab for two semesters.
RA = research assistant in a lab
The professor hired three RAs to help analyse the survey data.
As an RA, Renata runs experiments and helps write research papers.
The RA position paid for Ishaan's tuition and living expenses.
Each RA was assigned a specific section of the literature review.
用法筆記
Very common on university websites, job postings, and academic CVs. The full phrase 'research assistant' is preferred in formal writing.
4. short for residence assistant or resident assistant — a student trained to suppo
short for residence assistant or resident assistant — a student trained to support and advise other students living in a university dormitory or residence hall
Stephanie applied for the RA job in her dormitory building.
RA = residence assistant in a dorm
The RA on duty organised a study group for first-year students.
Each floor of the hall has an RA who lives with the students.
If you have a problem with your roommate, talk to your RA first.
Training for new RAs covers conflict resolution and first aid.
用法筆記
Primarily used on US college campuses. Some universities use the alternative abbreviation 'CA' (community assistant) or 'HA' (hall advisor).
5. short for rheumatoid arthritis — a long-term illness that causes pain, swelling,
short for rheumatoid arthritis — a long-term illness that causes pain, swelling, and stiffness in the joints because the body's immune system attacks healthy tissue
Sari was diagnosed with RA at the age of thirty-two.
RA = rheumatoid arthritis diagnosis
The new medication helped reduce the swelling caused by her RA.
RA often affects the small joints of the hands and feet first.
Eleni's RA symptoms improved after she started physical therapy.
Support groups can help people living with RA share helpful tips.
用法筆記
Common in medical records, patient information leaflets, and support communities. The abbreviation is widely understood among patients and healthcare workers.
常見錯誤
6. short for right ascension — a coordinate used in astronomy to locate stars and o
short for right ascension — a coordinate used in astronomy to locate stars and other celestial objects, measured eastward along the celestial equator
The star's RA is 6 hours, 45 minutes, and 8 seconds.
RA = right ascension coordinate
Astronomers use RA and declination together to map the night sky.
Reuben adjusted the telescope to match the RA of the galaxy.
The RA value increases as you look from west to east across the sky.
A star chart lists the RA for each visible object by season.
用法筆記
Standard notation in star catalogues, telescope apps, and astronomy textbooks. Always paired with declination (dec) to form a complete sky position.
7. short for Royal Academician — a member of the Royal Academy of Arts in London, a
short for Royal Academician — a member of the Royal Academy of Arts in London, a title given to distinguished artists
The painting was created by a well-known RA who specialises in portraits.
RA = Royal Academician, an art title
Painter Yuki was elected an RA in 2019 and exhibited at the Summer Exhibition.
The RA letters after an artist's name indicate membership in the Royal Academy.
The Royal Academy's annual show features work by both RAs and new artists.
用法筆記
Typically appears after an artist's name (e.g. 'John Smith RA') or in art-historical contexts. May also refer to the Royal Academy itself.
8. short for radium — a radioactive chemical element (symbol Ra) that was once used
short for radium — a radioactive chemical element (symbol Ra) that was once used in luminous paints and is now used in some medical treatments
The periodic table lists Ra as the symbol for radium.
RA (or Ra) = radium element abbreviation
Early watches used RA in the paint to make the dials glow at night.
Marie Curie discovered RA through years of work with uranium ore.
RA is no longer used in consumer products because of safety concerns.
Scientists wrote the decay equation using Ra to represent radium.
The symbol Ra appears on safety labels for radioactive materials.
Compounds containing Ra can be used to treat some types of bone cancer.
用法筆記
In chemistry contexts, the abbreviation is more often written as 'Ra' (capital R, lowercase a). 'RA' in all capitals typically refers to other meanings.