Webster's Revised Unabridged Dictionary · 1913

Filibuster

Filibuster , noun

[Sp. flibuster, flibustero, corrupted from English freebooter. See Freebooter.]

A lawless military adventurer, especially one in quest of plunder; a freebooter; -- originally applied to buccaneers infesting the Spanish American coasts, but introduced into common English to designate the followers of Lopez in his expedition to Cuba in 1851, and those of Walker in his expedition to Nicaragua, in 1855.

Filibuster , intransitive verb

1.
To act as a filibuster, or military freebooter. — Bartlett
2.
To delay legislation, by dilatory motions or other artifices. [political cant or slang, United States] — Bartlett