1core 
/ˈkoɚ/ noun
plural cores /ˈkoɚ/ noun [count] 1 : the central part of a fruit (such as an apple) that contains the seeds
▪ an apple core — see color picture 2 : the central part of something
▪ the core of a golf ball ▪ The pads have a foam core. ▪ the engine core ▪ the core of the galaxy ▪ The Earth's core is very different from its crust. ▪ the urban core [=the central part of a city] 3 : the most important or basic part of something
▪ Lack of money is the core of the problem. ▪ The core of the government's plan is to provide loans for small businesses. ▪ voters who form the core of the party ▪ The economy is at the very core of this year's election. — see also hard core 4 technical : a part that has been removed from a material for scientific study
▪ took a core sample of rock ▪ an ice core from the glacier 5 technical : the place in a nuclear reactor where the reaction takes place
▪ the reactor core
▪ an apple core — see color picture
▪ the core of a golf ball ▪ The pads have a foam core. ▪ the engine core ▪ the core of the galaxy ▪ The Earth's core is very different from its crust. ▪ the urban core [=the central part of a city]
▪ Lack of money is the core of the problem. ▪ The core of the government's plan is to provide loans for small businesses. ▪ voters who form the core of the party ▪ The economy is at the very core of this year's election. — see also hard core
▪ took a core sample of rock ▪ an ice core from the glacier
▪ the reactor core
to the core
: in a very complete or extreme way — used for emphasis ▪ He is patriotic to the core. [=he is extremely patriotic] ▪ Her family is English to the core. ▪ He's rotten to the core. [=he's a very bad/dishonest person] ▪ They were shaken to the core. [=extremely shaken/upset]
