to have need of; need

He requires medical care.

to call on authoritatively; order or enjoin to do something

to require an agent to account for money spent.

to ask for authoritatively or imperatively; demand.

to impose need or occasion for; make necessary or indispensable

The work required infinite patience.

to call for or exact as obligatory; ordain

The law requires annual income-tax returns.

to place under an obligation or necessity

The situation requires me to take immediate action.

Chiefly British . to desire; wish to have

Will you require tea at four o'clock?

to demand; impose obligation

to do as the law requires.

adjective

inessential , optional

adjective

appropriate , called for , compulsatory , compulsory , condign , demanded , deserved , due , enforced , essential , imperative , imperious , indispensable , just , mandatory , needed , needful , obligatory , prerequisite , prescribed , recommended , requisite , right , rightful , set , suitable , unavoidable , vital , necessary , coercive , compelling , deontic , de rigueur , forced , incumbent