Eyewitness - Vine's Expository Dictionary of New Testament Words
Eyewitness[ 1,,G845, autoptes ]
signifies seeing with one's own eyes" (autos, "self," and a form, optano, "to see"), Luke 1:2.
[ 2,,G2030, epoptes ]
primarily "an overseer" (epi, "over"), then, a "spectator, an eye-witness" of anything, is used in 2 Peter 1:16 of those who were present at the transfiguration of Christ. Among the Greeks the word was used of those who had attained to the third grade, the highest, of the Eleusinian mysteries, a religious cult at Eleusis, with its worship, rites, festival and pilgrimages; this brotherhood was open to all Greeks. In the Sept., Esther 5:1, where it is used of God as the Overseer and Preserver of all things. Cp. epopteuo, "to behold," 1 Peter 2:12; 1 Peter 3:2.