Definition of only :
1. Above all others; particularly.
2. Alone in its class; by itself; not associated with others of the same class or kind; as, an only child.
3. Hence, figuratively: Alone, by reason of superiority; preeminent; chief.
4. In one manner or degree; for one purpose alone; simply; merely; barely.
5. One alone; single; as, the only man present; his only occupation.
6. Save or except ( that); - an adversative used elliptically with or without that, and properly introducing a single fact or consideration.
7. Singly; without more; as, only- begotten.
8. So and no otherwise; no other than; exclusively; solely; wholly.
still, provided, all, and, however, besides, nothing but, unrivaled, separate, scarce, precisely, completely, unexampled, barely, isolated, include, individually, solely, wholly, unclassified, nonpareil, totally, unaccompanied, lonesome, tho, alone, companionless, unmatched, whole, plainly, hardly, simply, exactly, just, peerless, only if, further, unless, exclusively, but, severally, notwithstanding, one, altogether, matchless, just now, incomparable, same, save, solo, merely, entirely, unequaled, exclusive, singly, moreover, only when, nevertheless, utterly, unparalleled, particular, scarcely, that, except, yet
single (part of speech: adjective)