English Words Starting With R

• radiolysis

  nounC2
  /ˌreɪ.diˈɒl.ɪ.sɪs/The chemical decomposition of a substance caused by ionizing radiation.
• radioman

  nounLow
  /ˈreɪ.di.əʊ.mæn/A person, typically in military or maritime contexts, who operates radio equipment and handles communications.
• radiometeorograph

  nounVery low (Technical/Historical)
  /ˌreɪdiəʊˈmiːtiərəɡrɑːf/An instrument, typically carried by a balloon or other means, designed to record and transmit meteorological data (such as temperature, pressure, humidity) via radio signals.
• radiometer

  nounlow
  /ˌreɪ.diˈɒm.ɪ.tə(r)/A scientific instrument for detecting and measuring radiant energy, often using vanes that rotate when exposed to light or heat.
• radiometric dating

  nounC2
  /ˌreɪ.di.əʊˈmet.rɪk ˈdeɪ.tɪŋ/A scientific method for determining the age of materials by measuring the decay of radioactive isotopes.
• radiomicrometer

  nounC
  /ˌreɪdiəʊmaɪˈkrɒmɪtə/An instrument for measuring very small amounts of radiant energy.
• radionics

  nounLow
  /ˌreɪdiˈɒnɪks/A pseudoscience claiming to diagnose and treat diseases using electronic devices, often based on the principle that disease emits specific electromagnetic frequencies.
• radionuclide

  nounLow
  /ˌreɪ.di.əʊˈnjuː.klaɪd/An unstable atom that emits radiation as it decays to a stable form.
• radiopager

  nounVery Low
  /ˈreɪ.di.əʊˌpeɪ.dʒə(r)/A portable electronic device that receives short text or numeric messages via radio signals, typically used for alerting or contacting someone.
• radiophare

  nounC2 / Very Low
  /ˈreɪdiəʊˌfɛː/A radio beacon; a fixed, land-based radio transmitter that emits a characteristic signal for the purpose of navigation, direction finding, or identifying a location for ships, aircraft, or other receivers.
• radiopharmaceutical

  nounC2
  /ˌreɪdiəʊˌfɑːməˈsjuːtɪk(ə)l/A medicinal drug containing a radioactive substance, used in diagnosis and treatment, especially in nuclear medicine.
• radiophone

  nounverb-ambitransitiveVery low (archaic/technical historical term)
  /ˈreɪ.di.əʊ.fəʊn/An early device for transmitting or receiving sound using radio waves; a wireless telephone.
• radiophosphorus

  nounC2
  /ˌreɪdiəʊˈfɒsf(ə)rəs/A radioactive isotope of the element phosphorus, used as a tracer in biological and medical research.
• radiophotograph

  nounExtremely Rare / Obsolete
  /ˌreɪ.di.əʊˈfəʊ.tə.ɡrɑːf/A photograph transmitted by radio.
• radioscope

  nounVery Low / Archaic / Technical
  /ˈreɪ.di.əʊˌskəʊp/A medical device or instrument for viewing images created using radioactive substances.
• radioscopy

  nounVery Low Frequency / Technical / Historical
  /ˌreɪ.diˈɒs.kə.pi/The examination of objects by means of X-rays or other penetrating radiation, often in real time, to view internal structures.
• radiosensitizer

  nounVery Low / Specialized
  /ˌreɪ.di.əʊˈsen.sɪ.taɪ.zə/A substance or agent that makes cells, especially cancerous ones, more vulnerable to the damaging effects of radiation therapy.
• radiosodium

  nounVery Rare
  /ˌreɪ.di.əʊˈsəʊ.di.əm/A radioactive isotope of sodium, particularly sodium-24, used in medical and scientific research.
• radiosonde

  nounC1-C2 / Very Low Frequency (Specialist)
  /ˈreɪdiəʊˌsɒnd/A small, expendable instrument package suspended below a weather balloon that transmits meteorological data (e.g., temperature, pressure, humidity) by radio to a ground station.
• radiostrontium

  nounVery Low (C2+)
  /ˌreɪ.di.əʊˈstrɒn.ti.əm/a radioactive isotope of strontium (especially strontium-90), produced by nuclear fission and posing a serious environmental hazard due to its chemical similarity to calcium, which allows it to accumulate in bones.

Showing 301–320 of 5802 words.