If you are asked to rock a baby, please do not throw a stone at it. Instead, move the baby gently from side to side. If this doesn't calm the child, play some loud rock music.

When rocking a baby you move gently, but when you're told not to “rock the boat” the rocking movement referred to is more violent, enough to tip the boat over. This kind of motion has more in common with what you do when “rocking out” listening to music. A rock is also a lump of mineral, and if we say someone is "like a rock," we mean he's totally dependable.

Definitions of rock
  1. noun
    material consisting of the aggregate of minerals like those making up the Earth's crust
    “that mountain is solid rock
    synonyms: stone
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    hard metamorphic rock consisting essentially of interlocking quartz crystals
    road metal
    broken rock used for repairing or making roads
    sedimentary rock
    rock formed from consolidated clay sediments
    the granitelike rocks that form the outermost layer of the earth's crust; rich in silicon and aluminum
    rock that form the continuous lower layer of the earth's crust; rich in silicon and magnesium
    metamorphic rock
    rock altered by pressure and heat
    crushed rock, gravel
    rock fragments and pebbles
    nitrate-bearing rock or gravel of the sodium nitrate deposits of Chile and Peru
    (geology) sediment in which flat pebbles are uniformly tilted in the same direction
    pumice, pumice stone
    a light glass formed on the surface of some lavas; used as an abrasive
    fine-grained homogeneous rock (such as basalt) containing minerals undetectable by the naked eye
    fine-grained rock consisting of compacted clay particles
    a kind of sedimentary rock resembling marble or limestone but rich in magnesium carbonate
    emery rock, emery stone
    a mixture of emery dust and a binder; can be molded into grindstones
    conglomerate, pudding stone
    a composite rock made up of particles of varying size
    stone that occurs naturally in fields; often used as building material
    a granitic rock composed of quartz and mica
    calc-tufa, tufa
    a soft porous rock consisting of calcium carbonate deposited from springs rich in lime
    molten rock in the earth's crust
    igneous rock
    rock formed by the solidification of molten magma
    a sedimentary rock consisting mainly of calcium that was deposited by the remains of marine animals
    a hard crystalline metamorphic rock that takes a high polish; used for sculpture and as building material
    (geology) amass of fine-grained rock in which fossils, crystals, or gems are embedded
    a metamorphic rock composed chiefly of amphibole and plagioclase
    a sedimentary rock differing from shale in being bound by silica and from slate in having no slate cleavages
    arenaceous rock
    a sedimentary rock composed of sand
    argillaceous rock
    a sedimentary rock formed from clay deposits
    rudaceous rock
    a sedimentary rock formed of coarse-grained material
    marlite, marlstone
    metamorphic rock with approximately the same composition as marl
    hornfels, hornstone
    a fine-grained metamorphic rock formed by the action of heat on clay rocks
    coarse gravel laid to form a bed for streets and railroads
    bank gravel, pit run, pit-run gravel
    gravel as found in natural deposits
    coarse beach gravel of small waterworn stones and pebbles (or a stretch of shore covered with such gravel)
    a fine-grained metamorphic rock that can be split into thin layers
    a dark grey volcanic rock
    light-colored and fine-grained granitic rock consisting chiefly of quartz and feldspars
    a laminated metamorphic rock similar to granite
    any metamorphic rock that can be split into thin layers
    (geology) the matrix of fine-grained crystalline material in which larger crystals are embedded
    dark greyish extrusive rock
    batholite, batholith, pluton, plutonic rock
    large mass of intrusive igneous rock believed to have solidified deep within the earth
    a granular crystalline intrusive rock
    one of a family of granular intrusive rocks
    a form of igneous rock consisting of extremely coarse granite resulting from the crystallization of magma rich in rare elements
    a dark coarse-grained igneous rock consisting principally of olivine
    very acid volcanic rock
    volcanic rock
    extrusive igneous rock solidified near or on the surface of the Earth
    rottenstone, tripoli
    a weathered and decomposed siliceous limestone; in powdered form it is used in polishing
    verd antique, verde antique
    a dark green impure marble
    porphyritic rock, porphyry
    any igneous rock with crystals embedded in a finer groundmass of minerals
    a sedimentary rock formed by the deposition of successive layers of clay
    type of:
    material, stuff
    the tangible substance that goes into the makeup of a physical object
  2. noun
    a lump or mass of hard consolidated mineral matter
    “he threw a rock at me”
    synonyms: stone
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    Plymouth Rock
    a boulder in Plymouth supposed to be where the Pilgrims disembarked from the Mayflower
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    a stony meteor lacking chondrules
    solid unweathered rock lying beneath surface deposits of soil
    boulder, bowlder
    a large smooth mass of rock detached from its place of origin
    calculus, concretion
    a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body
    a rock of meteoric origin containing chondrules
    clastic rock
    (geology) a rock composed of broken pieces of older rocks
    crystal, crystallization
    a rock formed by the solidification of a substance; has regularly repeating internal structure; external plane faces
    rock produced by an intrusive process
    outcrop, outcropping, rock outcrop
    the part of a rock formation that appears above the surface of the surrounding land
    a small smooth rounded rock
    a rock created by petrifaction; an organic object infiltrated with mineral matter and preserved in its original form
    (geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock
    stepping stone
    a stone in a marsh or shallow water that can be stepped on in crossing
    a prominent rock or pile of rocks on a hill
    wall rock
    a rock immediately adjacent to a vein or fault
    whin, whinstone
    any of various hard colored rocks (especially rocks consisting of chert or basalt)
    (geology) a piece of rock of different origin from the igneous rock in which it is embedded
    something to which a mountain climber's rope can be secured
    bladder stone, cystolith
    a calculus formed in the bladder
    any of numerous minute rudimentary crystalline bodies of unknown composition found in glassy igneous rock
    a calculus occurring in the intestines
    bilestone, gallstone
    a calculus formed in the gall bladder or its ducts
    glacial boulder
    a boulder that has been carried by a glacier to a place far distant from its place of origin
    kidney stone, nephrolith, renal calculus, urinary calculus
    a calculus formed in the kidney
    an outcropping of rock that extends outward
    calculus in a salivary gland
    river boulder
    a boulder that has been carried by a river to a place remote from its place of origin
    shore boulder
    a boulder found on a shore remote from its place of origin
    salivary calculus, sialolith
    a stone formed in the salivary gland
    a urinary stone
    type of:
    natural object
    an object occurring naturally; not made by man
  3. noun
    (figurative) someone who is strong and stable and dependable
    “he was her rock during the crisis”
    “"Thou art Peter, and upon this rock I will build my church"--Gospel According to Matthew”
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    type of:
    good person
    a person who is good to other people
  4. verb
    move back and forth or sideways
    “the ship was rocking
    “She rocked back and forth on her feet”
    synonyms: shake, sway
    cause to move back and forth
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    move, rock, or sway from side to side
    rock, sway, or nod; usually involuntarily
    sway heavily or unsteadily
    move without being stable, as if threatening to fall
    type of:
    move back and forth
    move in one direction and then into the opposite direction
  5. verb
    cause to move back and forth
    rock the cradle”
    rock the baby”
    synonyms: sway
    shake, sway
    move back and forth or sideways
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    type of:
    displace, move
    cause to move or shift into a new position or place, both in a concrete and in an abstract sense
  6. noun
    pitching dangerously to one side
    synonyms: careen, sway, tilt
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    type of:
    lurch, pitch, pitching
    abrupt up-and-down motion (as caused by a ship or other conveyance)
  7. noun
    a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western
    rock is a generic term for the range of styles that evolved out of rock'n'roll.”
    synonyms: rock 'n' roll, rock and roll, rock music, rock'n'roll, rock-and-roll
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    heavy metal, heavy metal music
    loud and harsh sounding rock music with a strong beat; lyrics usually involve violent or fantastic imagery
    art rock, progressive rock
    a style of rock music that emerged in the 1970s; associated with attempts to combine rock with jazz and other forms; intended for listening and not dancing
    acid rock, psychedelic rock
    a musical style that emerged in the 1960s; rock music inspired by or related to drug-induced experience
    punk, punk rock
    rock music with deliberately offensive lyrics expressing anger and social alienation; in part a reaction against progressive rock
    type of:
    popular music, popular music genre
    any genre of music having wide appeal (but usually only for a short time)
  8. noun
    hard bright-colored stick candy (typically flavored with peppermint)
    synonyms: rock candy
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    type of:
    candy, confect
    a rich sweet made of flavored sugar and often combined with fruit or nuts
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