Having the characteristic of growing or occurring in clusters; forming or resembling clusters.
From 'cluster' + adjectival suffix '-y'. A descriptive adjective formed from the noun.
'-Y' is one of English's favorite ways to make adjectives—'cluster' becomes 'clustery,' 'frost' becomes 'frosty,' 'salt' becomes 'salty.' It's such a productive pattern that even nonsense words with '-y' sound like they might be real adjectives.
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