unimitable

un- +‎ imitable

unimitable (comparative more unimitable, superlative most unimitable)

1. That cannot be imitated.
   • 1825, Samuel Johnson, The Works of Samuel Johnson in Nine Volumes‎:

     But Falstaff, unimitated, unimitable Falstaff, how shall I describe thee! thou compound of sense and vice; of sense which may be admired, but not esteemed; of vice which may be despised, but hardly detested.

   • 1915, Aphra Behn, The Works of Aphra Behn, Vol. I (of 6)‎:

     […] I have seen a man the most severe of Johnson's Sect, sit with his Hat remov'd less than a hair's breadth from one sullen posture for almost three hours at The Alchymist; who at that excellent Play of Harry the Fourth (which yet I hope is far enough from Farce) hath very hardly kept his Doublet whole; but affectation hath always had a greater share both in the action and discourse of men than truth and judgement have; and for our Modern ones, except our most unimitable Laureat, I dare to say I know of none that write at such a formidable rate, but that a woman may well hope to reach their greatest heights.