I. adjective
1.
separated from others
the house was alone on a windy ridge
Synonyms: apart, detached, isolate, isolated, removed, unaccompanied
Related Word: out-of-the-way, private, remote, retired, secluded, withdrawn
Idioms: off the beaten track
Contrasted words: adjacent, close-by, near-at-hand, nearly, neighboring, nigh
2.
Synonyms: lone 1, lonely, lonesome, solitary
3.
having no equal or rival and being single in kind or excellence
a drug alone in its curative powers
Synonyms: matchless, only, peerless, unequaled, unique, unmatched, unparalleled, unrivaled; compare supreme
Related Word: inimitable; incomparable, unexcelled, unsurpassed; excellent, good, superior
Idioms: second to none
Contrasted words: common, commonplace, everyday, ordinary, usual; accustomed, conventional, customary, regular
4.
Synonyms: only 2, lone, singular, sole, solitary, solo, unexampled, unique, unrepeatable
II. adverb
Synonyms: only 1, but, entirely, exclusively, solely