What is "mash vat"

Mash \Mash\, v. t. [imp. & p. p. Mashed; p. pr. & vb. n. Mashing.] [Akin to G. meischen, maischen, to mash, mix, and prob. to mischen, E. mix. See 2d Mash.] To convert into a mash; to reduce to a soft pulpy state by beating or pressure; to bruise; to crush; as, to mash apples in a mill, or potatoes with a pestle. Specifically (Brewing), to convert, as malt, or malt and meal, into the mash which makes wort.

Mashing tub, a tub for making the mash in breweries and distilleries; -- called also mash tun, and mash vat.