Adjective

(en adjective)

Having to substance; actually existing; real; as, substantial life.

Not seeming or imaginary; not illusive; real; solid; true; veritable.

* "to do some substantial good, is the compensation for much incidental imperfection" - Cardinal Newman, The Rise and Progress of Universities

Corporeal; material; firm.

Having good substance; strong; stout; solid; firm; as, substantial cloth; a substantial fence or wall.

possessed of goods or an estate; moderately wealthy; responsible; as, a substantial freeholder.

Large in size, quantity, or value; as, a substantial amount of money; vast

Most important; essential.

Ample or full.

A substantial amount of people in this buliding

Significantly great.

Adjective

(en adjective)

Necessary.

Very important; of high importance.

* {{quote-magazine, date=2013-05-17

, author=George Monbiot, authorlink=George Monbiot , title=Money just makes the rich suffer , volume=188, issue=23, page=19 , magazine=(The Guardian Weekly) citation , passage=In order to grant the rich these pleasures, the social contract is reconfigured. The welfare state is dismantled. Essential public services are cut so that the rich may pay less tax. […]}}

Being in the basic form; showing its essence.

Don’t mind him being grumpy. That’s the essential Fred.

Really existing; existent.

* Webster (1623)

Is it true, that thou art but a name, / And no essential thing?

Such that each complementary region is irreducible, the boundary of each complementary region is incompressible by disks and monogons in the complementary region, and no leaf is a sphere or a torus bounding a solid torus in the manifold.

(medicine) Idiopathic.