From mesos (middle). To be at the midpoint, to be in the middle of. Used in John 7:14 when Jesus went to the temple in the middle of the Feast of Tabernacles.
Jesus appeared at the temple 'about the middle of the festival' (John 7:14) and began to teach. His timing was deliberate — not at the beginning when crowds would expect a teacher, nor at the end, but in the middle, demonstrating His sovereign authority over timing and occasion. Jesus does things on His schedule, not ours. This pattern appears throughout His ministry: He acts when the Father's time has come.