I. silt 1 /sɪlt/ BrE AmE noun [uncountable]
[ Date: 1400-1500 ; Origin: Probably from a Scandinavian language ]
sand, mud, soil etc that is carried in water and then settles at a bend in a river, an entrance to a port etc
II. silt 2 BrE AmE verb
silt up phrasal verb
if something silts up or is silted up, it becomes filled with silt:
The old harbour silted up years ago.