Etymograph

English

simultaneous

Simultaneous comes from Medieval Latin simultaneus ‘acting together’, from Latin simul ‘at the same time’, and ultimately from Proto-Indo-European *sem- ‘one, whole’.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*sem-1‘one, whole’root named by Wiktionary
  2. Latinc. 75 BCE–200 CEsimul2‘at the same time’
  3. Latinc. 75 BCE–200 CEsimultās3‘a coming together, convergence or intersection’
  4. Medieval Latinc. 600–1500simultaneus1‘acting together’
  5. Englishearliest quotation 1992simultaneous1

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, English simultaneous
  2. 2 Wiktionary, Latin simultas
  3. 3 Wiktionary, Latin simultaneus
  4. Earliest quotation in Wiktionary’s entry: 1992, Rudolf Mathias Schuster, Chicago: “As with the Lejeuneaceae, this pattern of massive speciation…”.

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*sem-Wiktionary, English simultaneous‘one, whole’root named by Wiktionary
  2. Latinc. 75 BCE–200 CEsimulWiktionary, Latin simultas‘at the same time’
  3. Latinc. 75 BCE–200 CEsimultāsWiktionary, Latin simultaneus‘a coming together, convergence or intersection’
  4. Medieval Latinc. 600–1500simultaneusWiktionary, English simultaneous‘acting together’
  5. Englishearliest quotation 1992simultaneousWiktionary, English simultaneous. Earliest quotation in Wiktionary’s entry: 1992, Rudolf Mathias Schuster, Chicago: “As with the Lejeuneaceae, this pattern of massive speciation…”

Linked words

through Proto-Indo-European *sem- ‘one, whole’

some, same, single, seem, similar, simple, simply, soft, sam, sincerely, resemble, assemble, resemblance, singular, simulation, anomaly, sincerity, semblance, assimilate, synapse, homology, homeopathic, hyphen, anomalous, insincere, sempre, simile, synchronise, homolog, simulacrum, 47 more

through Latin simul ‘at the same time’

ensemble, 1 more

Today it means

adj Happening at the same moment.

Sources

Sources: Wiktionary, “simultaneous”; the older steps come from the Wiktionary entries for Latin simultas, Latin simultaneus. 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 *sem- / simultaneous

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