Phrase guide

free radical

noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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No pronunciation record was provided for this word.

1

noun

Meaning 1

A molecule, ion or atom that has one or more unpaired electrons, and which is generally highly reactive (and therefore often occurs only as a transient species).

Definition source: English Wiktionary via Wiktextract

Topics: chemistry, natural-sciences, physical-sciences, physics

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule that has lost an electron and will stabilize itself by stealing an electron from a nearby molecule

Definition source: Princeton WordNet 3.0

Examples

  • in the body free radicals are high-energy particles that ricochet wildly and damage cells

Meaning relationships

Synonyms: radical

Antonyms: none provided

Broader terms: atom

History

Etymology

No etymology was provided for this word.

Across languages

Translations

17 source translations are retained for this English entry.

  • Chinese Mandarin: 自由基 (zìyóujī) — molecule, ion, or atom with an unpaired electron
  • Finnish: vapaa radikaali — molecule, ion, or atom with an unpaired electron
  • French: radical libre — molecule, ion, or atom with an unpaired electron
  • German: Radikal — molecule, ion, or atom with an unpaired electron
  • German: freies Radikal — molecule, ion, or atom with an unpaired electron
  • Hungarian: szabad gyök — molecule, ion, or atom with an unpaired electron
  • Indonesian: radikal bebas — molecule, ion, or atom with an unpaired electron
  • Italian: radicale libero — molecule, ion, or atom with an unpaired electron
  • Japanese: 遊離基 (yūriki) — molecule, ion, or atom with an unpaired electron
  • Korean: 유리기 (yurigi) — molecule, ion, or atom with an unpaired electron
  • Persian: رادیکال آزاد (râdikâl-e âzâd) — molecule, ion, or atom with an unpaired electron
  • Polish: wolny rodnik — molecule, ion, or atom with an unpaired electron
  • Portuguese: radical livre — molecule, ion, or atom with an unpaired electron
  • Spanish: radical libre — molecule, ion, or atom with an unpaired electron
  • Ukrainian: ві́льний радика́л (vílʹnyj radykál) — molecule, ion, or atom with an unpaired electron
  • Vietnamese: gốc tự do — molecule, ion, or atom with an unpaired electron
  • Welsh: radical rhydd — molecule, ion, or atom with an unpaired electron