Standard Lemma guide

conchoid

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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1

noun

Meaning 1

Any of a family of curves defined as the locus of points p, such that each p is on a line that passes through a given fixed point P and intersects a given curve, C, and the distance from p to the point of intersection with C is a specified constant (note that for nontrivial cases two such points p satisfy the criteria, and the resultant curve has two parts).

Definition source: English Wiktionary via Wiktextract

Topics: geometry, mathematics, sciences

Examples

  • The conchoid of a circle with respect to a point on the circle is a cardioid if the fixed distance is equal to the diameter of the circle.
  • The Conchoid of Nicomedes is the conchoid of a straight line with respect to a point not on the line.
  • 1815, Charles Hutton, Pappus, entry in A Philosophical and Mathematical Dictionary, Volume 2, page 147, He next treats of the properties of the Conchoid, which Nicomedes invented for doubling the cube; applying it to the solution of certain problems concerning Inclinations, with the finding of two mean proportionals, and cubes in any proportion whatever.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

A conchoidal fracture in rock.

Definition source: English Wiktionary via Wiktextract

Topics: geography, geology, natural-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

History

Etymology

From Latin concha (“mussel”) (from Ancient Greek κόγχη (kónkhē)) + -oid or directly from Ancient Greek κογχοειδής (konkhoeidḗs), referring to the curved outline of a mussel shell or anything in this form. By surface analysis, conch + -oid.

Across languages

Translations

3 source translations are retained for this English entry.

  • Czech: konchoida — any of a certain family of curves
  • Russian: конхо́ида (konxóida) — any of a certain family of curves
  • Turkish: konkoid — any of a certain family of curves