a railroad track (or its width) narrower than the standard 56.5 inches
limited in size or scope
make or become more narrow or restricted
lacking tolerance or flexibility or breadth of view
become more focus on an area of activity or field of study
become tight or as if tight
judge tentatively or form an estimate of (quantities or time)
a measuring instrument for measuring and indicating a quantity such as the thickness of wire or the amount of rain etc.