The Dictionary of Opera by Charles Osborne (Simon & Schuster: $22.95) covers the florid field pretty carefully, from Abbado to Zylis-Gara, in only 382 pages. Osborne's precise prose does embrace an occasional error. One of the more amusing ones claims that Hans Hotter sang Amneris in "Aida" (he was versatile, but surely not that versatile). Some of the photo choices must be regarded as esoteric. The basso czar chosen to illustrate "Boris Godunov," for example, is not Chaliapin, not Kipnis, not Pinza, not Ghiaurov, not Talvela or Nesterenko but one Tiit Kuuzik of Estonia. Even with its quirks and generally British orientation, however, this must be the most engaging single volume of its kind--also the most exhaustive, most picturesque and most up-to-date.