1To step or stride over something — lifting one leg to cross over a ditch, threshold, an obstacle, or a person's outstretched legs in a single step. Usually written in kana.
小さな溝をまたいで向こう側へ渡った。
I stepped over the small ditch and crossed to the other side.
敷居をまたいで座敷に上がった。
I stepped over the threshold and went up into the tatami room.
寝ている犬をまたいで通った。
I stepped over the sleeping dog as I passed.
水たまりをまたごうとして足を滑らせた。
I slipped while trying to step over the puddle.
2To span or stretch across — for a bridge or structure to extend over something, or for a matter to extend across two or more areas, years, or generations. Usually written in kana.
この橋は二つの県をまたいでいる。
This bridge spans two prefectures.
そのプロジェクトは年をまたいで続く見込みだ。
The project is expected to continue across the new year.
この研究は複数の分野をまたいでいる。
This research spans several fields.