Ancilla to the Pre-Socratic Philosophers, by Kathleen Freeman, , at sacred-texts.com
The Older Sophists: Name And Concept. These men were active during the latter part of the fifth and early part of the fourth centuries B.C.
'Sophistês' originally meant 'skilled craftsman' or 'wise man'. The specialised meaning 'professional teacher' did not come into use until the end of the fifth century B.C., the period of the travelling teachers. The bad sense of the word developed almost immediately; Aristotle summed up the Sophist's art as 'the appearance, not the reality, of wisdom', and the Sophist as one who makes money out of this pretence.
The title was nevertheless used in Roman Imperial times for 'professor' of rhetoric, or prose writer, without any bad meaning.