Meanings of clustered against in English

Far out, bluish, phantom-like sails clustered against the pallid horizon.

Danello, Tali, and Soek stood clustered against it, protected from the crowd by the thick pillar and the gate.

Stokes and the other household servants were clustered against one wall, clutching bags and hard cases and talking anxiously among themselves.

Clearer, more distinct they grew until feathery masses of pine-needles stood clustered against the sky like the wondrous rendering in a Japanese print.