simultaneous

From Medieval Latin simultaneus, from simultim (“at the same time, extended”), from Latin simul (“together, at the same time”); compare similar.

(UK) IPA^(key): /ˌsɪm.əlˈteɪ̯.ni.əs/, /ˌsɪm.əlˈteɪ̯.njəs/
(US) IPA^(key): /ˌsaɪ̯.məlˈteɪ̯.ni.əs/, /ˌsaɪ̯.məlˈteɪ̯.njəs/
- Audio (US): (file)
Rhymes: -eɪniəs, -eɪnɪəs

simultaneous (not comparable)

Happening at the same moment.
- 1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, Chicago, Ill.: Field Museum of Natural History, →ISBN, pages 3-4:
  As with the Lejeuneaceae, this pattern of massive speciation appears to be correlated with the Cretaceous explosion of the angiosperms and the simultaneous creation of a host of new microenvironments, differing in humidity, light intensity, texture, etc.
(mathematics, of a set of equations) To be solved for the same values of variables.

(antonym(s) of “happening at the same moment”): sequential, asynchronous, metachronous

occurring at the same time

Arabic: مُتَزَامِن (mutazāmin)
Belarusian: адначасо́вы (adnačasóvy)
Bulgarian: едновременен (bg) (ednovremenen)
Catalan: simultani (ca)
Chinese:
Mandarin: 同時 / 同时 (zh) (tóngshí)
Czech: současný (cs), souběžný (cs)
Danish: samtidig
Dutch: gelijktijdig (nl), simultaan (nl)
Esperanto: samtempa
Finnish: samanaikainen (fi)
French: simultané (fr)
Galician: simultáneo (gl)
Georgian: თანადროული (tanadrouli), ერთდროული (ertdrouli), იმავდროული (imavdrouli), ერთჟამიერი (ertžamieri)
German: gleichzeitig (de), simultan (de)
Greek: ταυτόχρονος (el) (taftóchronos)
Hungarian: egyidejű (hu), szimultán (hu)
Indonesian: bersamaan (id)
Italian: simultaneo (it), concomitante (it)
Japanese: 同時の (ja) (どうじの, dōji no)
Korean: 동시적인 (dongsijeogin)
Malay: serentak (ms)
Manx: coghleashagh
Maori: tautokorua, tukutahi, ngātahi, ngātatahi, tahi (mi)
Norwegian: samtidig (no), samstundes
Old English: samod
Polish: równoczesny (pl), jednoczesny (pl)
Portuguese: simultâneo (pt)
Russian: одновре́ме́нный (ru) (odnovréménnyj), синхро́нный (ru) (sinxrónnyj)
Scottish Gaelic: co-amail
Serbo-Croatian:
Cyrillic: си̏мулта̄н, исто̀времен, исто̀добан

Roman: sȉmultān (sh), istòvremen (sh), istòdoban (sh)
Spanish: simultáneo (es)
Swedish: samtidig (sv)
Tagalog: santaknain
Ukrainian: одноча́сний (odnočásnyj)

mathematics

English