Origin, source, inception, root, provenance, provenience, prime mover denote the point at which something (as a process, a growth, a development, a custom, a habit, or an institution) begins its course or its existence.
Origin applies chiefly to the point at which the thing under consideration has its rise or to the person or thing from which it is ultimately derived; it often applies specifically to the causes in operation before the thing itself is finally brought into being.
Often, when used in reference to persons, it means little more than ancestry or parentage; it is then used either in the singular or the plural.
Source basically applies to the point at which waters from a spring or fountain emerge to form the beginning point of a stream or river. In extended use source more often than origin applies to what serves as the ultimate beginning of a thing, especially an immaterial or intangible thing; however, since the term is sometimes qualified by such words as immediate or secondary which weaken or destroy this implication, it is often in this sense modified by ultimate, fundamental, or primary.
Source is also applied to the one (as the person, book, manuscript, or document) from which a person derives information; in this sense a primary source is a person who has firsthand knowledge or a work that was written at the time under discussion, especially by one who had firsthand knowledge; a secondary source is a person who has learned the facts from others or a work which is based upon information gathered from others.
Inception is often preferred to origin when the reference is to the actual beginning (as of an undertaking, a project, an institution, or a practice); the term carries a weaker connotation of underlying causes than origin, yet does not, as source often does, carry a suggestion that the thing so called is the ultimate origin.
Root often suggests that the actual origin of a thing goes back to something very deep and fundamental and that the thing itself is only an outward manifestation of its influence. Root therefore more often even than source applies to what is regarded as the first or final cause of a thing.
Provenance and provenience are chiefly used to designate the place or, sometimes, the race or people from which a thing is derived or where or by whom or among whom it originated or was invented or constructed.
Prime mover is chiefly used as a designation of an ultimate and original source of motion or motive power; when applied to a personal agent, it usually refers to an inciter or instigator of an action or course.
In mechanics the term specifically applies to the natural or mechanical power which sets a thing moving or in motion; it has been used in reference to wind (as in driving a sailing ship), steam (as in driving a steamship), a waterwheel, a windmill, or a steam or diesel engine.