NOUN (2)

1. a small round soft mass (as of chewed food);

2. a large pill; used especially in veterinary medicine;

The Collaborative International Dictionary of English v.0.48:

Bolus \Bo"lus\, n.; pl. Boluses. [L. bolus bit, morsel; cf. G.
   ? lump of earth. See Bole, n., clay.]
   A rounded mass of anything, esp. a large pill.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bolus
    n 1: a small round soft mass (as of chewed food)
    2: a large pill; used especially in veterinary medicine