Definition of "questionable"

A crude, cold rain was falling heavily; the spring-time presented itself as a questionable improvement.

1881, Henry James, Jr., chapter 3, in The Portrait of a Lady, New York, N.Y.: Houghton, Mifflin and Company […], page 28

[…] he had a love of money—a sort of acquisitiveness, that led him into questionable dealings.

1920, Carolyn Wells, chapter 18, in Raspberry Jam‎, Philadelphia: J.B. Lippincott, page 302

Thou com'ſt in ſuch a queſtionable ſhape / That I will ſpeake to thee.

c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene iv], page 257, column 1