In the context of 'binary blob' I think it would be clear it just means an amorphous mass of bits and not some Jargon File definition (which in turn is clearly a play on the regular word in itself).
Most (traditional) relational database servers do not support arbitrary sized (often >255 bytes) fields in a single row. The solution was to have a separate Large OBject heap, and store references to those LOBs in the actual rows.
Starkey claims that he invented the term, and that the acronym is actually a backronym. I've heard conflicting stories on that score.
