Longman Dictionary of Contemporary English - necessary

~1 adj 1 something that is necessary is what you need to have or need to do; essential  (I'll leave it to you to make all the necessary arrangements.) + for  (Food is necessary for life.) it is necessary (for sb) to do sth  (It's not necessary to wear a tie. | The doctor says it may be necessary for me to have an operation. | make it necessary (for sb) to do sth)  (The heavy rain made it necessary to close several roads. | is it really necessary to do sth? spoken (=used to complain about something that someone is doing))  (Is it really necessary to make all that noise! | if necessary (=if it is necessary):)  (I'll stay up all night, if necessary, to get it finished. | hardly necessary (=almost not necessary))  (Taking notes was hardly necessary - she had a brilliant memory.) 2 necessary connection/consequence etc a connection, result etc that must exist  (the necessary connection between wage rates and the price of food) 3 a necessary evil something bad or unpleasant that you have to accept in order to achieve what you want  (Mr Hurst regarded work as a necessary evil.) ~2 n 1 the necessaries things that you need, such as food or money, especially for a journey 2 do the necessary spoken to do what is necessary  (Leave it to me - I'll do the necessary.)