in·stant 
(ĭnstənt)
(ĭnstənt)n.
1. A period of time so short as to be almost imperceptible. See Synonyms at moment.
2. A particular or precise time: at the instant of combustion.
3. Abbr. inst. The current month: your letter of the 15th instant.
4. A food or beverage designed for quick preparation.
adj.
1. Occurring at once; immediate: instant gratification.
2. Imperative; urgent: an instant need.
3. Now under consideration; present.
4.
a. Commercially prepared or processed for quick and easy final preparation: an instant cake mix.
b. Appearing, done, or taking place with great quickness and ease: "She had the gift of instant intimacy" (Sylvia Jukes Morris).
c. Quickly and easily resolved or determined: instant lottery tickets.
adv.
At once; instantly.
[Middle English, from Old French, from Latin īnstāns, īnstant-, present, present participle of īnstāre, to approach : in-, on; see IN-2 + stāre, to stand; see stā- in the Appendix of Indo-European roots.]
instant·ness n.