"apparent displacement of an object observed, due to an actual displacement of the observer," 1570s, from French parallaxe (mid-16c.), from Greek parallaxis "change, alteration, inclination of two lines meeting at an angle," from parallassein "to alter, make things alternate," from para- (see para- (1)) + allassein "to change," from allos "other" (from PIE root *al- "beyond"). Related: Parallactic.
"to pass into or through without rupture or displacement," 1650s, from Latin permeatus, past participle of permeare "to pass through," from per "through" (from PIE root *per- (1) "forward," hence "through") + meare "to pass," from PIE root *mei- (1) "to change, go, move." Related: Permeated; permeating.
c. 1400, dislocacioun, "displacement of parts," originally of bones of the limbs, from Old French dislocacion (14c.), or directly from Medieval Latin dislocationem (nominative dislocatio), noun of action from past participle stem of dislocare "put out of place," from Latin dis- "away" (see dis-) + locare "to place," from locus "a place," which is of uncertain origin. General sense is from c. 1600.
early 15c., "passable" (of an area); "penetrable" (of a building)," from Late Latin permeabilis "that can be passed through, passable," from Latin permeare "to pass through, go over," from per "through" (from PIE root *per- (1) "forward," hence "through") + meare "to pass," from PIE root *mei- (1) "to change, go, move." Meaning "capable of being passed through without rupture or displacement" is from 1773, especially of substances permitting the passage of fluids. Related: Permeably.
"imaginary bad place," 1952, from dys- "bad, abnormal" + ending abstracted from utopia. Earlier in medical use, "displacement of an organ" (by 1844), with second element from Greek topos "place" (see topos). Dystopian was used in the non-medical sense in 1868 by J.S. Mill:
I may be permitted, as one who, in common with many of my betters, have been subjected to the charge of being Utopian, to congratulate the Government on having joined that goodly company. It is, perhaps, too complimentary to call them Utopians, they ought rather to be called dys-topians, cacotopians. What is commonly called Utopian is something too good to be practicable; but what they appear favour is too bad to be practicable. [speech, March 12, 1868]
Used by 17c. mystical writers for "a state of rapture that stupefied the body while the soul contemplated divine things," which probably helped the meaning shift to "exalted state of good feeling" (1610s). Slang use for the drug 3,4-methylendioxymethamphetamine dates from 1985. Formerly also spelled ecstasie, extacy, extasy, etc. Attempts to coin a verb to go with it include ecstasy (1620s), ecstatize (1650s), ecstasiate (1823), ecstasize (1830).