The word 'cluster' is both a noun (cluster, clusters), and a verb (cluster, clusters, clustering, clustered). Example uses:
Noun: The cyclists were still in a cluster as they reached the finish line.
Verb: We held our breath when the runners clustered, fearing someone would trip the others.
Race can be a verb or a noun. verb -- I will race you to the kitchen. The years seem to race by these days. noun -- Jack is running in the next race. There are two candidates left in the presidential race.
Racial means to be relating to race. An example sentence would be: She did not like their racial remarks at all.
Preexisting to our race, the humans, there were dinosaurs and many other creatures living on Earth.
Cluster of diamonds hung from the princess's ear.
I don't think you passed that homework assignment.She passed out at the sight of blood.Your friend passed you in the race.
The use of cluster bombs in Iraq was proving to be extremely deadly to the American troops.
There was a cluster of stars that the astronomers were studying carefully.
the race was consolation
There was a cluster (a lot) of balloons at my friends party, must be because she's turning 13.
Syria's government use the cluster bombs to annihilate the Syrian citizens
there are a group of stars that are cclose together
Did you see that cluster in the corner?
The race for the office of Mayor is on!
Let's race to the bauxite mine!
I came second in a race
Jack and Jill were looking at rings, Jill decided on a sapphire and diamond cluster.
"That horse went in the paddock before the race"