Function: add-mode-abbrev

Define mode-specific abbrev for last word(s) before point.
Argument is how many words before point form the expansion;
or zero means the region is the expansion.
A negative argument means to undefine the specified abbrev.
Reads the abbreviation in the minibuffer.

Don't use this function in a Lisp program; use `define-abbrev' instead. (fn ARG)