iamerican binary package in Ubuntu Bionic amd64

 This package provides the standard, medium-sized American English dictionary,
 based on the americanmed+ dictionary supplied with the source for ispell,
 with additional words added from the more comprehensive wamerican word
 list package.
 .
 There are also -small, -large, -huge, and -insane versions of this dictionary,
 and there are ibritish* packages as well.
 .
 The package also suggests wamerican because ispell's (L)ookup command
 needs a word list.

Source package