transient

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Passing with time; transitory.
• adjective Remaining in a place only a brief time.
• adjective Physics Decaying with time, especially as a simple exponential function of time.
• noun One that is transient, especially a hotel guest or boarder who stays for only a brief time.
• noun Physics A transient phenomenon or property, especially a transient electric current.

from The Century Dictionary.

• Passing across, as from one thing or person to another; communicated.
• Passing with time; of short duration; not permanent; not lasting or durable; temporary; as, a transient impression.
• Hasty; momentary; passing: as, a transient glance of a landscape.
• In music, intermediate—that is, serving as a connective, but unessential in itself: as, a transient chord, modulation, or note. Compare passing-note.
• SynonymsTransient, Transitory, Fleeting. Strictly, transient marks the fact that a thing soon passes or will soon pass away: as, a transient impression; a transient shadow. Transitory indicates that lack of permanence is in the nature of the thing; as, transitory pleasure; this transitory life. Fleeting is by figure a stronger word than transient, though in the same line of meaning. See list under transitory.
• noun One who or that which is temporary, passing, or not permanent.
• noun Specifically A transient gruest.

from the GNU version of the Collaborative International Dictionary of English.

• noun That which remains but for a brief time.
• adjective Passing before the sight or perception, or, as it were, moving over or across a space or scene viewed, and then disappearing; hence, of short duration; not permanent; not lasting or durable; not stationary; passing; fleeting; brief; transitory.
• adjective Hasty; momentary; imperfect; brief.
• adjective Colloq. U. S. Staying for a short time; not regular or permanent.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Passing or disappearing with time; transitory.
• adjective Remaining for only a brief time.
• adjective physics Decaying with time, especially exponentially.
• adjective mathematics having a positive probability of being left and never being visited again.
• adjective Occasional; isolated; one-off; individual.
• adjective Passing through; passing from one person to another.
• adjective philosophy Operating beyond itself; having an external effect.
• noun Something which is transient.
• noun physics A transient phenomenon, especially an electric current; a very brief surge.
• noun acoustics A relatively loud, non-repeating signal in an audio waveform which occurs very quickly, such as the attack of a snare drum.
• noun A person who passes through a place for a short time; a traveller; a migrant worker
• noun An unhoused person

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective of a mental act; causing effects outside the mind
• adjective lasting a very short time
• noun (physics) a short-lived oscillation in a system caused by a sudden change of voltage or current or load
• noun one who stays for only a short time