Sentence:  Jesus called them one by one: / Peter, Andrew, James and John. / Next came Philip, Thomas too, / Matthew and Bartholomew. / James the one they called the Less, / Simon, also Thaddeus. / Judas twelve <WSD>apostles</WSD> made / Jesus was by him betrayed. 
Meaning of the word marked with <WSD> tags:  A missionary, or leader of a religious mission, especially one in the early Christian Church (but see Apostle).