Webster's Revised Unabridged Dictionary · 1913

Observable

Observable , adjective

[Latin observabilis: compare French observable.]

1.
Capable of being observed; discernible; noticeable. — Sir. T. Browne
The difference is sufficiently observable. — Southey
2.
Worthy of being observed; important enough to be noted or celebrated; as, an observable anniversary.
3.
Noteworthy; remarkable.