The Collaborative International Dictionary of English v.0.48:
Shrewd \Shrewd\, a. [Compar. Shrewder; superl. Shrewdest.]
[Originally the p. p. of shrew, v.t.]
1. Inclining to shrew; disposing to curse or scold; hence,
vicious; malicious; evil; wicked; mischievous; vexatious;
rough; unfair; shrewish. [Obs.] --Chaucer.
[Egypt] hath many shrewd havens, because of the
great rocks that ben strong and dangerous to pass
by. --Sir J.
Every of this happy number
That have endured shrewd days and nights with us.
2. Artful; wily; cunning; arch.
These women are shrewd tempters with their tongues.
3. Able or clever in practical affairs; sharp in business;
astute; sharp-witted; sagacious; keen; as, a shrewd
observer; a shrewd design; a shrewd reply.
Professing to despise the ill opinion of mankind
creates a shrewd suspicion that we have deserved it.
Syn: Keen; critical; subtle; artful; astute; sagacious;
discerning; acute; penetrating.
Usage: Shrewd, Sagacious. One who is shrewd is keen to
detect errors, to penetrate disguises, to foresee and
guard against the selfishness of others. Shrewd is a
word of less dignity than sagacious, which implies a
comprehensive as well as penetrating mind, whereas
shrewd does not.
[1913 Webster] -- Shrewd"ly, adv. -- Shrewd"ness,