For instance at Matthew 24:3 the disciples asked Jesus
....Tell us, when shall these things be? and what shall be the sign of thy coming, and of the end of the world? (King James bible and the Living Bible)
.....end of the age? (New International Bible) and .....the close of the age? (Revised Standard Bible) ....the conclusion of the system of things? (NWT Bible) and also could be the end of the times or the end of the era. End of the world would give the wrong impression that it meant (then, at that time and moment) But it meant a period of time. Jesus gave us signs to look for such as nation would rise against nation and kingdom against kingdom, food shortages, earthquakes, etc. so that we would know that we were in the end of the times or the conclusion of the system of things.