re the doubtless Challenge game.
bolus - 'common', boluses - 'rare'
Isn't it slightly inconsistent that a noun and its regular plural should be classified differently?
In the same game, lotus and lotuses - were both classed as common
Irregular plurals are a different matter - (loti an alternative plural, for example is 'rare' in Chi), but I feel that regularly formed plurals - and regularly formed inflected verb forms - should have the same classification as their root.