• IPA: /ɪˈluːsɪv/

illusive

1. Subject to or pertaining to an illusion, often used in the sense of an unrealistic expectation or an unreachable goal or outcome.

   Testing software completely is an illusive goal.

   • 1912 January, Zane Grey, chapter 8, in Riders of the Purple Sage: A Novel, New York, N.Y.; London: Harper & Brothers Publishers, OCLC 6868219 ↗:

     […] he could not catch the illusive thing that had sadly perplexed as well as elevated his spirit.

• (pertaining to an illusion) illusory