or ‧ gan ‧ iz ‧ er BrE AmE ( also organiser British English ) /ˈɔːɡənaɪzə $ ˈɔːrɡənaɪzər/ noun [countable]
[ Word Family: noun : ↑ organization ≠ DISORGANIZATION , ↑ reorganization , ↑ organizer ; verb : ↑ organize ≠ DISORGANIZE , ↑ reorganize ; adjective : ↑ organizational , ↑ organized ≠ ↑ disorganized ]
someone who makes the arrangements for something that is planned to happen:
The organizers had expected about 50,000 people to attend the concert.