1. [adj]  highly unusual or rare but not the single instance; "spoke with a unique accent"; "had unique ability in raising funds"; "a frankness unique in literature"; "a unique dining experience"
2. [adj]  radically distinctive and without equal; "he is alone in the field of microbiology"; "this theory is altogether alone in its penetration of the problem"; "Bach was unique in his handling of counterpoint"; "craftsmen whose skill is unequaled"; "unparalleled athletic ability"; "a breakdown of law unparalleled in our history"
3. [adj]  the single one of its kind; "a singular example"; "the unique existing example of Donne's handwriting"; "a unique copy of an ancient manuscript"; "certain types of problems have unique solutions"

UNIQUE is a 6 letter word that starts with U.

1. \U*nique"\, a. [F. unique; cf. It. unico; from L. unicus,
   from unus one. See {One}.]
   Being without a like or equal; unmatched; unequaled;
   unparalleled; single in kind or excellence; sole. --
   {U*nique"ly}, adv. -- {U*nique"ness}, n.
   
   

2. \U*nique"\, n.
   A thing without a like; something unequaled or unparalleled.
   [R.]
   
         The phenix, the unique pf birds.         --De Quincey.
   
   

A portable job control language.

["The UNIQUE Command Language - Portable Job Control", I.A. Newman, Proc DATAFAIR 73, 1973, pp. 353-357].