SIMULTANEITY
simultaneity, simultaneousness
(noun) happening or existing or done at the same time
Source: WordNet® 3.1
Etymology
Noun
simultaneity (countable and uncountable, plural simultaneities)
The quality or state of being simultaneous; simultaneousness.
(music) More than one complete musical texture occurring at the same time. This first appeared in the music of Charles Ives, and is common in the music of Conlon Nancarrow, and others.
Synonyms
• (state of being simultaneous): concurrentness, synchroneity; see also simultaneousness
Source: Wiktionary
Si`mul*ta*ne"i*ty, n.
Definition: The quality or state of being simultaneous; simultaneousness.
Source: Webster’s Unabridged Dictionary 1913 Edition