indispensable

Absolutely necessary; essential.

Obligatory; unavoidable.

One that is indispensable.

Not to be set aside, evaded, or escaped; inevitable.

Not to be dispensed with; not to be omitted or spared; absolutely necessary or requisite.

Not permissible by dispensation or license; incapable of being legalized.

An indispensable person or thing.

Specifically, trousers.

A bag or pocket, frequently of silk and much decorated, worn by women in the first years of the nineteenth century, on the outside of the gown, instead of inside, as an ordinary pocket would be.

Not dispensable; impossible to be omitted, remitted, or spared; absolutely necessary or requisite.