1. someone who expresses in language
    someone who talks (especially someone who delivers a public speech or someone especially garrulous)

    e.g. the speaker at commencement
           an utterer of useful maxims

    Synonym: speakertalkerverbalizerverbaliser

2. someone who circulates forged banknotes or counterfeit coins

3. an organism that can utter vocal sounds

    e.g. an utterer of foul oaths
           is the giraffe a vocalizer?

    Synonym: vocalizervocaliser