1 : 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"
2 : (informal) strikingly unconventional
3 : being the only one; single and isolated from others; "the lone doctor in the entire county"; "a lonesome pine"; "an only child"; "the sole heir"; "the sole example"; "a solitary instance of cowardice"; "a solitary speck in the sky"
4 : beyond or deviating from the usual or expected; "a curious hybrid accent"; "her speech has a funny twang"; "they have some funny ideas about war"; "had an odd name"; "the peculiar aromatic odor of cloves"; "something definitely queer about this town"; "what a rum fellow"; "singular behavior"
5 : 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"