absolutely necessary; indispensable

Discipline is essential in an army.

pertaining to or constituting the essence of a thing.

noting or containing an essence of a plant, drug, etc.

being such by its very nature or in the highest sense; natural; spontaneous

essential happiness.

Mathematics .

(of a singularity of a function of a complex variable) noting that the Laurent series at the point has an infinite number of terms with negative powers.

(of a discontinuity) noting that the function is discontinuous and has no limit at the point. Compare removable ( def. 2 ) .

a basic, indispensable, or necessary element; chief point

Concentrate on essentials rather than details.

adjective

accessory , auxiliary , inessential , minor , nonessential , secondary , subsidiary , unimportant , atypical

noun

accessory , auxiliary , nonessential , subsidiary , throwaway , trivia

adjective

capital , cardinal , chief , constitutive , crucial , foremost , fundamental , imperative , indispensable , leading , main , necessary , necessitous , needed , needful , prerequisite , principal , required , requisite , right-hand , wantednotes:the words crucial , essential , and vital cannot be qualified (cannot be more or less...) , absolute , basal , cold , complete , congenital , connate , constitutional , deep-seated , elemental , elementary , ideal , inborn , inbred , inherent , innate , intrinsic , key , material , meat and potatoes * , name of the game * , nitty-gritty * , nub , perfect , primary , prime , primitive , quintessential , substratal , underlyingnotes:the words crucial , basic , integral , vital , ultimate , underlying

noun

abcs , bottom line * , brass tacks * , condition , element , essence , fire and ice , fundamental , groceries * , guts * , heart , meat and potatoes * , must , name of the game * , nitty-gritty * , nuts and bolts * , part and parcel , precondition , prerequisite , principle , quintessence , requirement , requisite , rudiment , sine qua non , stuff , substance , vital part , where one’s atnotes:the words crucial , essential , and vital cannot be qualified (cannot be more or less...) , basic , necessity , need , chief , constitutive , elementary , imperative , important , inherent , integral , intrinsic , key , substantive , vital