simultaneous

adjective si·mul·ta·neous \ˌsī-məl-ˈtā-nē-əs, -nyəs also ˌsi-\

: happening at the same time

Full Definition of SIMULTANEOUS

: existing or occurring at the same time : exactly coincident

: satisfied by the same values of the variables <simultaneous equations>

— si·mul·ta·ne·i·ty \-tə-ˈnē-ə-tē, -ˈnā-\ noun

— si·mul·ta·neous·ly \-ˈtā-nē-əs-lē, -nyəs-\ adverb

— si·mul·ta·neous·ness noun

See simultaneous defined for English-language learners

See simultaneous defined for kids

Origin of SIMULTANEOUS

Latin simul at the same time + English -taneous (as in instantaneous) — more at same

First Known Use: circa 1660

Related to SIMULTANEOUS

Synonyms: coetaneous, coeval, coexistent, coexisting, coextensive, coincident, coincidental, concurrent, contemporaneous, coterminous, contemporary, synchronic, synchronous

Antonyms: asynchronous, noncontemporary, nonsimultaneous, nonsynchronous

Synonym Discussion of SIMULTANEOUS

contemporary, contemporaneous, coeval, synchronous, simultaneous, coincident mean existing or occurring at the same time. contemporary is likely to apply to people and what relates to them <Abraham Lincoln was contemporary with Charles Darwin>. contemporaneous is more often applied to events than to people <contemporaneous accounts of the kidnapping>. coeval refers usually to periods, ages, eras, eons <two stars thought to be coeval>. synchronous implies exact correspondence in time and especially in periodic intervals <synchronous timepieces>. simultaneous implies correspondence in a moment of time <the two shots were simultaneous>. coincident is applied to events and may be used in order to avoid implication of causal relationship <the end of World War II was coincident with a great vintage year>.