Obsolete vs. Archaic — What's the Difference?

No longer in use

Also Archaic Relating to, being, or characteristic of a much earlier, often more primitive period, especially one that develops into a classical stage of civilization

Outmoded in design, style, or construction

No longer current or applicable; antiquated

(Biology) Vestigial or rudimentary, especially in comparison with related or ancestral species, as the tailbone of an ape. Used of an organ or other part of an organism.

Relating to, being, or characteristic of words and language that were once in regular use but are now relatively rare and suggestive of an earlier style or period.

To cause to become obsolete

Relating to or being an early or premodern evolutionary form of an organism or group of organisms

(of words, equipment, etc.) No longer in use; gone into disuse; disused or neglected (often in favour of something newer).

Relating to or being an early form of Homo sapiens or a closely related species, such as Neanderthal, that is anatomically distinct from modern humans.

(biology) Imperfectly developed; not very distinct.

Archaic Relating to a Native American culture prevalent throughout much of North America from about 8000 BC to about 1000 BC, characterized especially by the development of Mesolithic tools and by the increased reliance on smaller game animals as the large Pleistocene mammals became extinct.

To cause to become obsolete.

A member of an archaic population of Homo.

No longer in use; gone into disuse; disused; neglected; as, an obsolete word; an obsolete statute; - applied chiefly to words, writings, or observances.

A general term for the prehistoric period intermediate between the earliest period (‘[http://en.wikipedia.org/wiki/Paleo-Indian Paleo-Indian]’, ‘Paleo-American’, ‘American‐paleolithic’, &c.) of human presence in the Western Hemisphere, and the most recent prehistoric period (‘Woodland’, etc.).

Not very distinct; obscure; rudimental; imperfectly developed; abortive.

(paleoanthropology) (A member of) an archaic variety of Homo sapiens.

To become obsolete; to go out of use.

Of or characterized by antiquity; old-fashioned, quaint, antiquated.

Old; no longer in use or valid or fashionable;

(of words) No longer in ordinary use, though still used occasionally to give a sense of antiquity and are still likely to be understood by well-educated speakers and are found in historical texts.

No longer in use;

(archaeology) Belonging to the archaic period

Of or characterized by antiquity or archaism; antiquated; obsolescent.

So extremely old as seeming to belong to an earlier period;

Little evolved from or characteristic of an earlier ancestral type;