There are two ways in which mulvoc can be triggered, one as you finish
typing each word, and one at the end of every Emacs command, including
mulvoc-cursor-active non-nil causes translations of the
word at point to be displayed at every command. This happens in
buffers in which
mulvoc-setup-hook-function has been run.
mulvoc-abbrev-active non-nil causes the abbreviation
expansion mechanism to display translations of known words as they are