a cloud, used figuratively for a vast, dense throng of people
This word is the older, poetic Greek term for a cloud, and it appears just once in the New Testament: Hebrews 12:1, where the faithful of the previous chapter are called a great "cloud of witnesses" surrounding the reader. It is not a weather report. Since Homer, Greek writers had used "cloud" as a vivid picture of a crowd so huge and packed together that it loses individual shape, like a swarm or an advancing army that darkens the sky. Hebrews reaches for that classical image on purpose.
The author could have used the ordinary New Testament word for cloud (νεφέλη), but deliberately chose this rarer one. The ordinary word carries the heavy memory of God's presence:
- the cloud at Mount Sinai
- the pillar that led Israel
- the cloud of glory in the temple
- the figure coming "with the clouds" in Daniel
By avoiding that word here, Hebrews keeps those associations out of the picture. The witnesses press in on the runner not as a divine presence but as an immense weight of accumulated faith, the way a great host encircles a battlefield.
The surrounding language of 12:1 to 2 adds a second layer: a footrace, the runner stripping off every weight, the watching crowd. Many readers picture the heroes of faith as spectators ringing an arena, cheering the runner home. That stadium picture comes from the race imagery around the word, not strictly from the word itself, and scholars are careful about how hard to press it.