Definition of "slubber"

[…] he [Antonio] answered, do not so, Slubber not business for my sake, Bassanio, But stay the very riping of the time

c. 1596–1598 (date written), William Shakespeare, “The Merchant of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene viii], page 171

There is no art that hath more […] slubbered with aphorisming pedantry than the art of policy.

1641 May, John Milton, Of Reformation Touching Church-Discipline in England: And the Cavvses that hitherto have Hindred it; republished as Will Taliaferro Hale, editor, Of Reformation Touching Church-Discipline in England (Yale Studies in English; LIV), New Haven, Conn.: Yale University Press, 1916

It grows colder, and grayer, and penguins cry in the night, and huge amphibians moan and slubber.

1914, Jack London, chapter 33, in Mutiny of the Elsinore