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.

Primary Meanings of rock

material consisting of the aggregate of minerals like those making up the Earth's crust
move back and forth or sideways
pitching dangerously to one side
a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western
hard bright-colored stick candy (typically flavored with peppermint)
Full Definitions of rock

n material consisting of the aggregate of minerals like those making up the Earth's crust

“that mountain is solid rock
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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

n a lump or mass of hard consolidated mineral matter

“he threw a rock at me”
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

n (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”
Type of:
good person
a person who is good to other people

v move back and forth or sideways

“the ship was rocking
“She rocked back and forth on her feet”
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

v cause to move back and forth

rock the cradle”
rock the baby”
shake, sway
move back and forth or sideways
Type of:
displace, move
cause to move or shift into a new position or place, both in a concrete and in an abstract sense

n pitching dangerously to one side

careen, sway, tilt
Type of:
lurch, pitch, pitching
abrupt up-and-down motion (as caused by a ship or other conveyance)

n 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.”
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)

n hard bright-colored stick candy (typically flavored with peppermint)

rock candy
Type of:
candy, confect
a rich sweet made of flavored sugar and often combined with fruit or nuts