the GNU version of the Collaborative International Dictionary of English
n. The first martyr; the first who suffers, or is sacrificed, in any cause; -- applied esp. to Stephen, the first Christian martyr.
The Century Dictionary and Cyclopedia
n. The first martyr; the first of any series of martyrs; the first who suffers or is sacrificed in any cause; specifically, Stephen, the earliest Christian martyr.
Word Usage
"Στέφανος is known as the protomartyr of Christianity and venerated by the Roman Catholic,"