Knock v. i. [imp. & p. p. Knocked p. pr. & vb. n. Knocking.]
 1. To drive or be driven against something; to strike against something; to clash; as, one heavy body knocks against another.
 2. To strike or beat with something hard or heavy; to rap; as, to knock with a club; to knock on the door.
    For harbor at a thousand doors they knocked.   --Dryden.
    Seek, and ye shall find; knock, and it shall be opened unto you.   --Matt. vii. 7.
 3. To practice evil speaking or fault-finding; to criticize habitually or captiously. [Slang, U. S.]
 To knock about, to go about, taking knocks or rough usage; to wander about; to saunter. [Colloq.] “Knocking about town.” --W. Irving.
 To knock up, to fail of strength; to become wearied or worn out, as with labor; to give out. “The horses were beginning to knock up under the fatigue of such severe service.” --De Quincey.
 To knock off, to cease, as from work; to desist.
 To knock under, to yield; to submit; to acknowledge one's self conquered; -- an expression probably borrowed from the practice of knocking under the table with the knuckles, when conquered. “Colonel Esmond knocked under to his fate.” --Thackeray.


 Knock v. t.
 1. To strike with something hard or heavy; to move by striking; to drive (a thing) against something; as, to knock a ball with a bat; to knock the head against a post; to knock a lamp off the table.
    When heroes knock their knotty heads together.   --Rowe.
 2. To strike for admittance; to rap upon, as a door.
    Master, knock the door hard.   --Shak.
 3. To impress strongly or forcibly; to astonish; to move to admiration or applause. [Slang, Eng.]
 To knock in the head, or To knock on the head, to stun or kill by a blow upon the head; hence, to put am end to; to defeat, as a scheme or project; to frustrate; to quash. [Colloq.]
 To knock off. (a) To force off by a blow or by beating. (b) To assign to a bidder at an auction, by a blow on the counter. (c) To leave off (work, etc.). [Colloq.]
 To knock out, to force out by a blow or by blows; as, to knock out the brains.
 To knock up. (a) To arouse by knocking. (b) To beat or tire out; to fatigue till unable to do more; as, the men were entirely knocked up. [Colloq.] “The day being exceedingly hot, the want of food had knocked up my followers.” --Petherick. (c) Bookbinding To make even at the edges, or to shape into book form, as printed sheets. (d) To make pregnant.  Often used in passive, "she got knocked up". [vulgar]