The BBI-993 was a type of Earth starship that was utilized during the 22nd century.
The SS Buckaroo Banzai, launched in 2137, was a vessel of this class. (TNG: "Up The Long Ladder")
Background
The name of this ship type appeared on an Okudagram that appeared on Picard's desk monitor, and was not verbally referenced on screen. A legible version of the Okudagram would appear in the reference book, Star Trek: The Next Generation - The Continuing Mission.
BBI-993 is a reference to the movie The Adventures of Buckaroo Banzai Across the 8th Dimension.