frequent/rare/common occurrence• The Millers said bears in the camp are a rare occurrence.• In practice parents' associations are incredibly supportive and these problems are a rare occurrence.• Worse, a spokesman for the Treasuryimplies this is a frequent occurrence.• Clearly, crime is not a rare occurrence, but it is hidden methodically, and this raises problems for research.• The annualcompetition saw quite a rare occurrence in the sport of fishing.• This is probably a comparatively rare occurrence for small mammals, but it certainly does occur.• This was, of course, an extremely rare occurrence.• Because of the frequent occurrence of kept, this causes difficulties in quantitativeanalysis.