I. ˈōn-lē adjective
Etymology: Middle English, from Old English ānlīc, from ān one — more at one
Date: before 12th century
1. : unquestionably the best : peerless
2.
a. : alone in a class or category : sole
the only one left
the only known species
b. : having no brother or sister
an only child
3. : few
one of the only areas not yet explored
II. adverb
Date: 14th century
1.
a. : as a single fact or instance and nothing more or different : merely
has only lost one election — George Orwell
b. : solely , exclusively
known only to him
2. : at the very least
it was only too true
3.
a. : in the final outcome
will only make you sick
b. : with nevertheless the final result
won the battles, only to lose the war
4.
a. : as recently as : not before
only last week
only in the last year did she get recognition
b. : in the immediate past
only just talked to her
Usage:
The placement of only in a sentence has been a source of studious commentary since the 18th century, most of it intended to prove by force of argument that prevailing standard usage is wrong. After 200 years of preachment the following observations may be made: the position of only in standard spoken English is not fixed, since ambiguity is avoided through sentence stress; in casual prose that keeps close to the rhythms of speech only is often placed where it would be in speech; and in edited and more formal prose only tends to be placed immediately before the word or words it modifies.
III. conjunction
Date: 14th century
1.
a. : with the restriction that : but
you may go, only come back early
b. : and yet : however
they look very nice, only we can't use them
2. : were it not that : except
I'd introduce you to her, only you'd win her — Jack London