noun Radar.
the effect on a radarscope of the fluctuation of a radar echo because of alternating interference and reinforcement of the reflected waves.

bob1 + -ing1 Unabridged


1 [bob]
a short, jerky motion: a bob of the head.
verb (used with object), bobbed, bobbing.
to move quickly down and up: to bob the head.
to indicate with such a motion: to bob a greeting.
verb (used without object), bobbed, bobbing.
to make a jerky motion with the head or body.
to move about with jerky, usually rising and falling motions: The ball bobbed upon the waves.
Verb phrases
bob up, to emerge or appear, especially unexpectedly: A familiar face bobbed up in the crowd.

1400–50; late Middle English bobben. See bob2


2 [bob]
a style of short haircut for women and children.
a docked horse's tail.
a dangling or terminal object, as the weight on a pendulum or a plumb line.
a short, simple line in a verse or song, especially a short refrain or coda.
a knot of worms, rags, etc., on a string.
a float for a fishing line.
a bobsled or bob skate.
Scot. a bunch, cluster, or wad, especially a small bouquet of flowers.
Obsolete, walking beam.
verb (used with object), bobbed, bobbing.
to cut short; dock: They bobbed their hair to be in style.
verb (used without object), bobbed, bobbing.
to try to snatch floating or dangling objects with the teeth: to bob for apples.
Angling. to fish with a bob.

1300–50; Middle English bobbe (noun) spray, cluster, bunch (of leaves, flowers, fruit, etc.); of uncertain origin


3 [bob]
a tap; light blow.
a polishing wheel of leather, felt, or the like.
verb (used with object), bobbed, bobbing.
to tap; strike lightly.

1350–1400; Middle English bobben to strike, beat, perhaps imitative See bop2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To Bobbing
World English Dictionary
bob1 (bɒb)
vb (usually foll by up) (usually foll by for) , bobs, bobbing, bobbed
1.  to move or cause to move up and down repeatedly, as while floating in water
2.  to move or cause to move with a short abrupt movement, as of the head
3.  to make (a bow or curtsy): the little girl bobbed before the visitor
4.  to appear or emerge suddenly
5.  (intr; foll by under, below, etc) to disappear suddenly, as beneath a surface
6.  to attempt to get hold (of a floating or hanging object, esp an apple) in the teeth as a game
7.  a short abrupt movement, as of the head
8.  a quick curtsy or bow
9.  bell-ringing a particular set of changes
10.  angling
 a.  short for bobfloat
 b.  the topmost fly on a cast of three, often fished bobbing at the surface
 c.  this position on a wet-fly cast
[C14: of uncertain origin]

bob2 (bɒb)
1.  a hairstyle for women and children in which the hair is cut short evenly all round the head
2.  a dangling or hanging object, such as the weight on a pendulum or on a plumb line
3.  a polishing disc on a rotating spindle. It is usually made of felt, leather, etc, impregnated with an abrasive material
4.  bob skate short for bobsleigh
5.  a runner or pair of runners on a bobsled
6.  angling a small knot of worms, maggots, etc, used as bait
7.  a very short line of verse at the end of a stanza or preceding a rhyming quatrain (the wheel) at the end of a stanza
8.  a refrain or burden with such a short line or lines
9.  a docked tail, esp of a horse
10.  dialect (Brit) a hanging cluster, as of flowers or ribbons
vb , bobs, bobbing, bobbed
11.  (tr) to cut (the hair) in a bob
12.  (tr) to cut short (something, esp the tail of an animal); dock or crop
13.  (intr) to ride on a bobsled
[C14 bobbe bunch of flowers, perhaps of Celtic origin]

bob3 (bɒb)
vb , bobs, bobbing, bobbed
1.  to tap or cause to tap or knock lightly (against)
2.  a light knock; tap
[C13 bobben to rap, beat; see bop²]

bob4 (bɒb)
n , pl bob
(Brit) (formerly) an informal word for a shilling
[C19: of unknown origin]

Bob (bɒb)
slang Bob's your uncle everything is or will turn out all right
[C19: perhaps from pet form of Robert]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

"short, jerking motion," late 14c., probably connected to M.E. bobben "to strike, beat" (late 13c.), perhaps of echoic origin. Another early sense was "to make a fool of, cheat" (early 14c.). As a slang word for "shilling" it is attested from 1789, but the signification is unknown.

"short hair," 1680s, attested 1570s in sense of "a horse's tail cut short," from earlier bobbe "cluster" (as of leaves), mid-14c., a northern word, perhaps of Celtic origin (cf. Ir. baban "tassel, cluster," Gael. babag). Used over the years in various senses connected by the notion of "round, hanging
mass," e.g. the meaning "weight at the end of a line" (1650s). The hair sense was revived with a shift in women's styles early 20c. (verb 1918, noun 1926). Related words include bobby pin, bobby socks, bobsled.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Abbreviations & Acronyms
  1. best of breed

  2. Bolivia—boliviano

  3. Bureau of the Budget

The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Example sentences
You've seen plastic containers washed up on the beach or bobbing around docks.
The next day they were all bobbing in the dark water, dead.
Even if driven underground for a while, they have an unsettling habit of
  bobbing up later.
The crane's arm is now completely outstretched and the bucket is bobbing up and
  down precariously.
Related Words
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