We don't have synonyms for imbankment yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are embankment, embarkment and impackment.
(n) :
Obsolete form of embankment. [a long mound of earth, stone, or similar material, usually built for purposes such as to hold back or store water, for protection from weather or enemies, or to support a road or railway.]
(n) :
Obsolete form of embankment. [a long mound of earth, stone, or similar material, usually built for purposes such as to hold back or store water, for protection from weather or enemies, or to support a road or railway.]