a trough just below the eaves of a roof or at the side of a street to catch and carry off rainwater, surface water, etc
a trough or groove to catch or direct something, e.g. at the side of a bowling alley
a white space between two pages of a book, two postage stamps on a sheet, etc
(the gutter) the lowest or most vulgar level or condition of human life
[Middle English goter via early French goutiere from Latin gutta drop]