[Fr.; see also BACK sb.2]

1

  1.  A flat-bottomed French ferry-boat; a ferry.

2

1672.  Coles, Bac, a ferry.

3

1753.  Chambers, Cycl. Supp., Bac, in navigation, is used for a praam, or ferry-boat.

4

1867.  in Smyth, Sailor’s Word-bk. [Cf. ‘St. Augustine’s Back’ at Bristol.]

5

  2.  In Brewing and Distilling: see BACK sb.2

6