Origin

This character combines water (the left component, shown as three drops) with a sound hint on the right. The right component sounds like "chō," which became the on'yomi reading. Since tides are the rhythmic movement of ocean water driven by the sun and moon, and the right component originally referred to morning or the sun's rising, the pairing makes sense: water plus this sound element creates a character for the flowing tides that rise and fall with the sun's cycle. Over time, the meaning expanded to include "opportunity," perhaps because tides represent moments when conditions are right for action.