What is "to beat the rap"

Beat \Beat\, v. i.

1. To strike repeatedly; to inflict repeated blows; to knock vigorously or loudly.

   The men of the city . . . beat at the door.
   --Judges. xix. 2

2. 2. To move with pulsation or throbbing.

   A thousand hearts beat happily.
   --Byron.

3. To come or act with violence; to dash or fall with force; to strike anything, as rain, wind, and waves do.

   Sees rolling tempests vainly beat below.
   --Dryden.

   They [winds] beat at the crazy casement.
   --Longfellow.

   The sun beat upon the head of Jonah, that he fainted, and wished in himself to die.
   --Jonah iv. 8.

   Public envy seemeth to beat chiefly upon ministers.
   --Bacon.

4. To be in agitation or doubt. [Poetic]

   To still my beating mind.
   --Shak.

5. (Naut.) To make progress against the wind, by sailing in a zigzag line or traverse.

6. To make a sound when struck; as, the drums beat.

7. (Mil.) To make a succession of strokes on a drum; as, the drummers beat to call soldiers to their quarters.

8. (Acoustics & Mus.) To sound with more or less rapid alternations of greater and less intensity, so as to produce a pulsating effect; -- said of instruments, tones, or vibrations, not perfectly in unison.

   A beating wind (Naut.), a wind which necessitates tacking in order to make progress.

   To beat about, to try to find; to search by various means or ways.
   --Addison.

   To beat about the bush, to approach a subject circuitously.

   To beat up and down (Hunting), to run first one way and then another; -- said of a stag.

   To beat up for recruits, to go diligently about in order to get helpers or participators in an enterprise.

   To beat the rap, to be acquitted of an accusation; -- especially, by some sly or deceptive means, rather than to be proven innocent.