What is "to drink to the health of"

Drink \Drink\, v. t.

1. To swallow (a liquid); to receive, as a fluid, into the stomach; to imbibe; as, to drink milk or water.

   There lies she with the blessed gods in bliss, There drinks the nectar with ambrosia mixed.
   --Spenser.

   The bowl of punch which was brewed and drunk in Mrs. Betty's room.
   --Thackeray.

2. To take in (a liquid), in any manner; to suck up; to absorb; to imbibe.

   And let the purple violets drink the stream.
   --Dryden.

3. To take in; to receive within one, through the senses; to inhale; to hear; to see.

   To drink the cooler air,
   --Tennyson.

   My ears have not yet drunk a hundred words Of that tongue's utterance.
   --Shak.

   Let me . . . drink delicious poison from thy eye.
   --Pope.

4. To smoke, as tobacco. [Obs.]

   And some men now live ninety years and past, Who never drank to tobacco first nor last.
   --Taylor (1630.)

   To drink down, to act on by drinking; to reduce or subdue; as, to drink down unkindness.
   --Shak.

   To drink in, to take into one's self by drinking, or as by drinking; to receive and appropriate as in satisfaction of thirst. ``Song was the form of literature which he [Burns] had drunk in from his cradle.''
   --J. C. Shairp.

   To drink off or To drink up, to drink completely, especially at one draught; as, to drink off a cup of cordial.

   To drink the health of, or To drink to the health of, to drink while expressing good wishes for the health or welfare of.