If the master option is set in any fashion (via the command line, the ASPELL_CONF environment variable, or a configuration file) Aspell will look for a dictionary of that name. If one could not be found, it will complain.
Otherwise it will use the value of the lang option to search for an appropriate dictionary. If more than one dictionary is found for the given language string then it will look for a dictionary with a matching variety if the variety option is set. If it is not set it will look for a dictionary without a variety. If after matching the lang and variety there is still more than one dictionary available it will find one with the size closest to the value of the size option. The default size is 60. If Aspell cannot find a dictionary based on the lang option then it will give up and complain.
If the lang option is not explicitly set its value will be
based on the LC_MESSAGES locale. This locale is generally taken
from the LC_MESSAGES environment variable or the LANG
environment variable if LC_MESSAGES is not set. However, if
Aspell is being used as a library from within another program which
already explicitly set the locale then it will use the locale of the
library rather than the environment variables. If Aspell cannot
determine the language from the LC_MESSAGES locale than it will
The list option dict-alias can be used to influence which dictionary is selected by creating an alias from one dictionary name to another. This option is most useful when there is more than one dictionary for a given language. For example `add-dict-alias en_US en_US-w_accents' will cause Aspell to choose the accented version of the American English dictionary instead of the non-accented version. To add an alias use:
add-dict-alias NAME VAL