blast 1. vt.,n. Synonym for {BLT}, used esp. for large data sends over a network or comm line. Opposite of {snarf}. Usage: uncommon. The variant `blat' has been reported. 2. vt. [HP/Apollo] Synonymous with {nuke} (sense 3). Sometimes the message `Unable to kill all processes. Blast them (y/n)?' would appear in the command window upon logout.