The story
Named after the Dutch village that was home to its inventors, Onno Janssens and Willem Boegem.
Etymology from Wiktionary, CC BY-SA 4.0.
Muiderberg
Today it means: A bidding convention, a two-level preemptive opening based on a two-suiter with precisely a five-card major and a minor suit (four-card or longer). The 2♥ opening denotes five hearts and an unknown minor suit, whilst 2♠ denotes five spades and an unknown minor suit. Full definition →