narrow2 [intransitive and transitive]
to make something narrower or to become narrower:
He narrowed his eyes and gazed at the horizon.
The track divided into two and narrowed.
if a range, difference etc narrows, or if something narrows it, it becomes less:
The choice of goods available is narrowing.
The economic gap between the two halves of the country was beginning to narrow.
narrow something ↔ downphrasal verb
The police have narrowed down their list of suspects.
narrow something ↔ down to
I've narrowed it down to one of two people.