Definition of narrowest:
(adj) :
Having a small width; not wide; having opposite edges or sides that are close, especially by comparison to length or depth.
(adj) :
Of little extent; very limited; circumscribed.
(adj) :
(figuratively) Restrictive; without flexibility or latitude.
(adj) :
Having a small margin or degree.
(v) :
(transitive) To reduce in width or extent; to contract.
(v) :
(intransitive) To get narrower.