What does acinus mean?
The definition of acinus
Ac”i*nus, n.; pl. Acini.
Etym: [L., grape, grapestone.]

1 (Bot.)

(a) One of the small grains or drupelets which make up some kinds of fruit, as the blackberry, raspberry, etc.
(b) A grapestone.

2 (Anat.)
One of the granular masses which constitute a racemose or compound gland, as the pancreas; also, one of the saccular recesses in the lobules of a racemose gland. Quain.