a person who contributes to the fulfillment of a need or furtherance of an effort or purpose; "my invaluable assistant"; "they hired additional help to finish the work"
someone who assists a priest or minister in a liturgical service; a cleric ordained in the highest of the minor orders in the Roman Catholic Church but not in the Anglican Church or the Eastern Orthodox Churches
someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous); "the speaker at commencement"; "an utterer of useful maxims"
the presiding officer of a deliberative assembly; "the leader of the majority party is the Speaker of the House of Representatives"