[intransitive,transitive]to become smaller in size, number, etc.; to make something smaller in size, number, etc.Temperatures decrease as we go from low to high elevation.Poverty rates decreased sharply up to the late 1960s.decrease somethingAnother way of decreasing the risks of reproductive cancers would be to use hormonal treatments. decrease (something) by somethingAt 35% O₂, plant growth decreased by about 20%.decrease (something) (from something) (to something)The rate of union membership has decreased from 10.1% in 1990 to 8.3% in 2003 (OECD, 2004).decrease (something) in somethingBecause of this, the lakes began to decrease in salinity.oppositeincrease1Collocationsdecrease + nounrate • level • number,amount • size • risk,likelihood,probability • incidence,frequency • cost,price • value • concentration • content • activity • performance • temperature • time • demand • consumptionIf the concentration of important nutrients decreases, cells respond by decreasing their growth rate. Companies may use temporary contracts so that managers can increase or decrease the number of staff as needed.noun + decreaserate,level • value • size • percentage,ratio • intensity • temperature • concentration,density • pressure • mortality • population • content • cost,priceAs explained by Boyle's law, as the aircraft climbs, the cabin pressure decreases compared with sea level. The quality of sugar diminished, and the sugar percentage decreased, so that the soft drinks had to be artificially sweetened.adverb + decrease | decrease + adverbsignificantly,substantially • dramatically,drastically • sharply • markedly • considerably • greatly • rapidly • slightly • gradually,steadily • progressively • exponentially • linearlyThe findings provide evidence that the vaccination programme significantly decreased hepatitis in infants. Energy expenditure has decreased markedly because of changes in the urban environment. Its peak sales years were in the 1950s and early 1960s, and since then sales have steadily decreased.