to be or become many: to grow large in number or quantity, and so to be abundant or great.
At heart this verb is about amount, not size. It is the word Hebrew reaches for when something is counted and the count runs high, or when a quantity swells. That marks it off from גדל, which is about being great in size, weight, or importance: a thing can grow with גדל while staying single, but a thing this verb describes has become many.
Its uses fan out into three close shades: being many (foes, sins, or a nation's works all standing in large number), becoming many over time (people spreading across the land, a harvest increasing, flocks breeding by the thousand), and being great in sheer extent (the outcry of a wicked city, or a countryside emptied of its people). The line between them is soft, because a large number and a swelling amount are the same idea seen from different angles.
The word lives almost entirely in poetry, and it leans toward a handful of subjects:
- enemies who have grown too many to face, in the laments of the Psalms
- sins and rebellions piling up against God, in the prophets
- the works of God, so many they defy counting, in praise
It is the quieter, mostly poetic partner of the everyday verb רבה, which covers the same ground and adds the active side, to make many or increase, including the famous command to be fruitful and multiply. The two words are so close that they share forms and fill in each other's gaps.