1. Abounding in aphoristic expressions.
2. A native or inhabitant of Poland.

For 1: After Polonius, a courtier and the father of Ophelia in Shakespeare's play Hamlet, known for his moralistic apothegms. Earliest documented use: 1847.
For 2: From Latin Polonia (Poland). Earliest documented use: 1533.
Some of Shakespeare's best-known quotations come out of Polonius's mouth. As his son Laertes heads for France, Polonius advises:

"Neither a borrower nor a lender be,
For loan oft loses both itself and friend."

"This above all: to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man."

At another time, he says: "Brevity is the soul of wit."
As happens with quotations, some of his words have become simplified and sharpened with time, such as from the original "For the apparel oft proclaims the man." to "Clothes make the man."
"A few Polonian precepts can do something to indicate whether or not a scientist is cut out for collaboration."
P.B. Medawar; Advice To A Young Scientist; Harper and Row; 1980.

POOLONIAN - a press pool reporter whose reportal wit comes entirely from the book "Zippy Words of Awesome Cliches for the Dull".