These words are applied to things to actions that do not occur often. Occasional means happening now and then at irregular intervals, and it carries the idea that recurrence can be expected: to make occasional trips to a museum; to attend an occasional cocktail party. Infrequent means occurring at greater intervals, and it neither suggests nor precludes recurrence: Total solar eclipses are infrequent .

Rare and uncommon go a step further than occasional and infrequent in that they are applied to that which is met with so seldom as to approach the unique.

• It is rare to find wisdom in the young; Snow in Melbourne is an uncommon slight; The kiwi is now rare in all but some forested parts of New Zealand; That was an uncommon act of charity.

Rare has the added sense of precious: a rare medieval manuscript; a rare sapphire.

Scattered and sporadic both mean occurring in space or time in an irregular or random pattern. Scattered emphasizes things that are part of a group but are situated with large, unequal spaces between them: scattered homesteads on the sheep-grazing plains; scattered showers; scattered applause from a bored audience. On the other hand, sporadic describes things that occur here and there with little or no continuity: sporadic outbreaks of hepatitis; sporadic sniper fire from roof-tops.