Simple past tense and past participle of cluster.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "clustered" in a sentence
"A quick aside: the term clustered index means something different in Oracle than in SQL"
"And they lend themselves to being built in clustered development styles that would quickly lead to reduced driving in compact areas."
"There's a huge difference between shooting an accurate arrow from the target line and shooting one at an animal over broken terrain clustered with brush, trees, and boulders."