Standard Lemma guide

viroid

noun · 3 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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1

noun

Meaning 1

Any of many short sections of RNA, but without the protein coat typical of viruses (the capsid), that are plant pathogens.

Definition source: English Wiktionary via Wiktextract

Topics: biology, microbiology, natural-sciences, virology

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: Viroidales

Antonyms: none provided

2

noun

Meaning 2

Any of certain defective viruses, such as hepatitis D, a human pathogen.

Definition source: English Wiktionary via Wiktextract

Topics: biology, microbiology, natural-sciences, virology

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

noun

Meaning 3

the smallest of viruses; a plant virus with its RNA arranged in a circular chromosome without a protein coat

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: virusoid

Antonyms: none provided

Broader terms: plant virus

History

Etymology

From virus + -oid.

Across languages

Translations

6 source translations are retained for this English entry.

  • Czech: viroid — certain defective viruses
  • French: viroïde — certain defective viruses
  • Icelandic: veirungur — certain defective viruses
  • Japanese: ウイロイド (uiroido) — certain defective viruses
  • Japanese: ウイルス様体 (uirusu yōtai) — certain defective viruses
  • Portuguese: viroide — certain defective viruses