arch- Also arche- and archi-.
Chief; principal; pre-eminent of its kind.
[Greek arkhi- or arkhe-, from arkhos, chief.]
The main meaning is that of the most important or highest ranking person of a given type, as in archduke, archdeacon, archangel, and archbishop. An architect is literally the ‘chief builder’, from Greek tektōn, builder.
A secondary sense uses the prefix in a critical or dismissive way to mean somebody who holds extreme views, or is the worst kind of something, or the ringleader of a group. Examples are arch-enemy, arch-fiend, arch-criminal, arch-reactionary, arch-rival, and arch-villain.
An archegonium (Greek gonos, race) is the female sex organ in mosses, liverworts, ferns, and most conifers. In archetype (tupos, model), the Greek prefix has a meaning more like ‘original’ or ‘primitive’, hence one of its meanings—the original pattern or model for something. The word architrave (Latin trabs, a beam) came from classical architecture, in which it was a main beam resting across the tops of columns.
Archive comes from a Greek word for public records; it derives from the related arkhē, government.