(1):

(superl.) Cheerful; genial; as, a sunny disposition.

(2):

(superl.) Of or pertaining to the sun; proceeding from, or resembling the sun; hence, shining; bright; brilliant; radiant.

(3):

(superl.) Exposed to the rays of the sun; brightened or warmed by the direct rays of the sun; as, a sunny room; the sunny side of a hill.

(4):

(n.) See Sunfish (b).