попутном

In a sentence

• Я встретил Сергея на попутном автобусе.

  I met Sergey on a passing bus.

  Here, 'попутном' describes an incidental or passing bus that was heading in the same direction as the speaker's route.

• В ходе попутного разговора мы обсудили наши планы.

  During a casual conversation, we discussed our plans.

  In this case, 'попутного' relates to a coincidental or casual conversation occurring naturally alongside some other activity.

• Попутным ветром наш корабль достиг берега быстрее.

  With a favorable wind, our ship reached the shore faster.

  Here, 'попутным' refers to a favorable wind that is assisting the ship's travel direction.