extrinsic

exterior, external, extraneous, extrinsic

1. The four words are related, and all have meanings based on outside. Exterior and external both refer to the outside of things in contrast to the inside

• (Most manufacturers describe their exterior wall paints as masonry paint —Do It Yourself Magazine, 1991)

and medicine is for external use when it is applied to the outside of the body; but exterior is generally physical only, whereas external is also applied in abstract or figurative meanings

• (Changes in staff, changes in curriculum and increasing external demands making planning a chancy business —M. Sullivan, 1991)

the external world is the world beyond one's perception. As a noun, however, exterior has the abstract meaning ‘the outward or apparent behaviour or demeanour of a person’:

• How about your pal Ivan? Does he have sensitive feelings under that Neanderthal exterior? —D. Ramsay, 1973

• Bob, who hides a sparky humour behind a grizzled exterior, said tenants who were taking his beers were doing it on a ‘belligerent, sod-the-brewer basis’ —What's brewing?, 1991.

External is used as a noun generally in the plural to mean ‘the outward aspects or circumstances’:

• The place has all the appropriate externals, chimneys choked with ivy, windows with jasmine, worm-eaten shutters, mossy thatch —P. Tristam, 1989

• Eventually he found all forms of religion involving ‘externals’ and ordinances unsatisfying —Dictionary of National Biography, 1993

• Add to that his inability to nail the externals of his characters' lives and his failure to conjure the campus mood (never mind the national zeitgeist), and the result is a disappointingly empty novel —weblog, IndE 2004.

2. Something that is extraneous is introduced or added from outside and is foreign to the object or entity in which it finds itself. Uses are both physical and abstract:

• Several other insects attach extraneous objects or material to themselves, but for very different reasons —M. & T. Birkhead, 1989

• A moment later any extraneous thoughts were driven from his mind —I. Watson, 1993.

Extraneous points are irrelevant matters brought into a discussion from which they have been excluded or to which they do not properly belong:

• We were properly prevented by the law from making any extraneous comment beyond what we had agreed with Ian and his lawyers —Liverpool Daily Echo, 2005.

Something that is extrinsic is not an essential and inherent part of the thing in question, and is often contrasted with intrinsic:

• Motivation may be considered as either intrinsic or extrinsic; intrinsic motives include those of exploration and curiosity, and extrinsic those of status and social approval —B. O'Connell, 1973

• Your personal belongings may be frugal and of little extrinsic value, but when they are lost or stolen, the cost of replacement can be surprisingly high —S. Meredeen, 1988.