Background
来自Big Physics
wiktionary
back + ground
etymonline
background (n.)
"the ground or situation to the rear of what is in front or most engaging of the attention," 1670s, from back (adj.) + ground (n.); original sense was theatrical, later applied to painting ("part of a picture representing what is furthest from the spectator"), 1752. Figurative sense is first attested 1854.
