Adjective

(en adjective)

Relating to the basic, essential or fundamental part of something.

Relating to an elementary school.

(physics) Relating to a subatomic particle.

* {{quote-magazine, date=2012-03

, author=(Jeremy Bernstein) , title=A Palette of Particles , volume=100, issue=2, page=146 , magazine=(American Scientist) citation , passage=The physics of elementary particles in the 20th century was distinguished by the observation of particles whose existence had been predicted by theorists sometimes decades earlier.}}

(archaic) Sublunary; not celestial; belonging to the sublunary sphere, to which the four classical elements (earth, air, fire and water) were confined; composed of or pertaining to these four elements.

Adjective

(en adjective)

(ecclesiastical, obsolete) Not admitting ecclesiastical dispensation; not subject to release or exemption; that cannot be allowed by bending the canonical rules.

The law was moral and indispensable . -Bp. Burnet

Absolutely necessary or requisite; that one cannot do without.

An indispensable component of a heart-healthy diet.

* {{quote-book, year=2006, author=

, title=Internal Combustion , chapter=2 citation , passage=But through the oligopoly, charcoal fuel proliferated throughout London's trades and industries. By the 1200s, brewers and bakers, tilemakers, glassblowers, pottery producers, and a range of other craftsmen all became hour-to-hour consumers of charcoal. This only magnified the indispensable nature of the oligopolists.}}