a chemical substance that is present at the start of a chemical reaction
realgar
Noun
a rare soft orange mineral consisting of arsenic sulphide
red clay
Noun
clay whose redness results from iron oxide
red fire
Noun
combustible material (usually salts of lithium or strontium) that burns bright red
regosol
Noun
a type of soil consisting of unconsolidated material from freshly deposited alluvium or sand
regur
Noun
a rich black loam of India
regur soil
Noun
a rich black loam of India
residual soil
Noun
the soil that is remaining after the soluble elements have been dissolved
residual clay
Noun
the soil that is remaining after the soluble elements have been dissolved
resinoid
Noun
a plastic containing resins
rhodochrosite
Noun
a mineral consisting of manganese carbonate
rhodonite
Noun
a pink or red mineral consisting of crystalline manganese silicate
ribose
Noun
a pentose sugar important as a component of ribonucleic acid
ricin
Noun
a toxic protein extracted from castor beans
ricin toxin
Noun
a toxic protein extracted from castor beans
road metal
Noun
broken rock used for repairing or making roads
rudaceous rock
Noun
a sedimentary rock formed of coarse-grained material
rust inhibitor
Noun
antioxidant that inhibits the formation of rust
recombinant protein
Noun
a protein derived from recombinant DNA
rocket fuel
Noun
an explosive charge that propels a rocket
rocket propellant
Noun
an explosive charge that propels a rocket
ratsbane
Noun
a white powdered poisonous trioxide of arsenic
rock wool
Noun
a light fibrous material used as an insulator
rawhide
Noun
untanned hide especially of cattle
rennet
Noun
a substance that curdles milk in making cheese and junket
royal jelly
Noun
a secretion of the pharyngeal glands of bees that is fed to very young larvae and to bees destined to be queens
ricinoleic acid
Noun
an oily fatty acid found in castor oil and used in soap
reagent
Noun
a chemical agent for use in chemical reactions
reducing agent
Noun
a substance capable of bringing about the reduction of another substance as it itself is oxidized
reductant
Noun
a substance capable of bringing about the reduction of another substance as it itself is oxidized
rolling paper
Noun
a strong tissue paper that burns evenly and is sufficiently porous to control the burning of the tobacco in a cigarette
reinforced concrete
Noun
concrete with metal and/or mesh added to provide extra support against stresses
ribonucleic acid
Noun
(biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes
refuse
Noun
food that is discarded (as from a kitchen)
refuse
Verb
show unwillingness towards
refuse
Verb
refuse to let have
refuse
Verb
refuse to accept
refuse
Verb
refuse entrance or membership
refuse
Verb
elude, especially in a baffling way
refuse
Verb
resist immunologically the introduction of some foreign tissue or organ
rheum
Noun
a watery discharge from the mucous membranes (especially from the eyes or nose)
recombinant deoxyribonucleic acid
Noun
genetically engineered DNA made by recombining fragments of DNA from different organisms
recombinant DNA
Noun
genetically engineered DNA made by recombining fragments of DNA from different organisms
ribonuclease
Noun
a transferase that catalyzes the hydrolysis of ribonucleic acid
ribonucleinase
Noun
a transferase that catalyzes the hydrolysis of ribonucleic acid
rubble
Noun
the remains of something that has been destroyed or broken up
radioactive dust
Noun
the radioactive particles that settle to the ground after a nuclear explosion
rose oil
Noun
a volatile fragrant oil obtained from fresh roses by steam distillation
resin
Noun
any of a class of solid or semisolid viscous substances obtained either as exudations from certain plants or prepared by polymerization of simple molecules
rosin
Noun
any of a class of solid or semisolid viscous substances obtained either as exudations from certain plants or prepared by polymerization of simple molecules