This is the 1946th most frequent Russian word.
рубежом
"Рубежом" means "border" or "threshold" in English.
Here 'рубежом' refers to a geographic or physical border.
Мы пересекли рубежом границу двух стран.
We crossed the border between two countries.
In this instance, 'рубежом' symbolizes a milestone or significant point.
Он всегда ставит себе целью достичь нового рубежа в своих достижениях.
He always sets a goal to reach a new milestone in his achievements.
Here 'рубежом' implies a historical or significant turning point.