Etymograph

English

explanandum

Explanandum comes from Latin explānō ‘to flatten or spread out’, from plānus ‘level, flat, even’, and ultimately from Proto-Indo-European *pleh₂-.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*pleh₂-1‘flat’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*pl̥h₂nós1reconstructed
  3. Proto-Italicc. 1500–700 BCE*plānos1reconstructed
  4. Latinc. 75 BCE–200 CEplānus1‘level, flat, even’
  5. Latinc. 75 BCE–200 CEexplānō2as explanandum‘to flatten or spread out’
  6. Englishearliest quotation 2024explanandum2

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin explano
  2. 2 Wiktionary, English explanandum
  3. Earliest quotation in Wiktionary’s entry: 2024, Scott Alexander Howard, The Other Valley: “Yet the most convincing thing was not this sense…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*pleh₂-Wiktionary, Latin explano‘flat’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*pl̥h₂nósWiktionary, Latin explanoreconstructed
  3. Proto-Italicc. 1500–700 BCE*plānosWiktionary, Latin explanoreconstructed
  4. Latinc. 75 BCE–200 CEplānusWiktionary, Latin explano‘level, flat, even’
  5. Latinc. 75 BCE–200 CEexplānōWiktionary, English explanandumas explanandum‘to flatten or spread out’
  6. Englishearliest quotation 2024explanandumWiktionary, English explanandum. Earliest quotation in Wiktionary’s entry: 2024, Scott Alexander Howard, The Other Valley: “Yet the most convincing thing was not this sense…”

Linked words

through Proto-Indo-European *pleh₂- ‘flat’

field, floor, palm, planet, clan, archipelago, fluke, parma, playa, placenta, palatine, flounder, lech, pelagic, placate, implacable, polonium, flay, veld, plantar, floe, purdah, planta, 46 more

through Proto-Italic *plānos

plane, planar, 11 more

through Latin plānus ‘level, flat, even’

plan, plain, llano, 13 more

through Latin explānō ‘to flatten or spread out’

explanation, explanatory, esplanade, unexplainable, explainable, 3 more

Today it means

noun That which is to be explained (cf. explanans).

Sources

Sources: Wiktionary, “explanandum”; the older steps come from the Wiktionary entry for Latin explano. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *pleh₂- / explanandum

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