From The Collaborative International Dictionary of English v.0.48:
Welter \Wel"ter\, v. i. [imp. & p. p. Weltered; p. pr. & vb. n. Weltering.] [Freq. of OE. walten to roll over, AS. wealtan; akin to LG. weltern, G. walzen to roll, to waltz, sich w[aum]lzen to welter, OHG. walzan to roll, Icel. velta, Dan. v[ae]lte, Sw. v[aum]ltra, v[aum]lta; cf. Goth. waltjan; probably akin to E. wallow, well, v. i. [root]146. See Well, v. i., and cf. Waltz.] [1913 Webster] 1. To roll, as the body of an animal; to tumble about, especially in anything foul or defiling; to wallow. [1913 Webster]
When we welter in pleasures and idleness, then we eat and drink with drunkards. --Latimer. [1913 Webster]
These wizards welter in wealth's waves. --Spenser. [1913 Webster]
He must not float upon his watery bier Unwept, and welter to the parching wind, Without the meed of some melodious tear. --Milton. [1913 Webster]
The priests at the altar . . . weltering in their blood. --Landor. [1913 Webster]
2. To rise and fall, as waves; to tumble over, as billows. "The weltering waves." --Milton. [1913 Webster]
Waves that, hardly weltering, die away. --Wordsworth. [1913 Webster]
Through this blindly weltering sea. --Trench. [1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Welter \Wel"ter\, v. t. [Cf. Wilt, v. i.] To wither; to wilt. [R.] [1913 Webster]
Weltered hearts and blighted . . . memories. --I. Taylor. [1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Welter \Wel"ter\, a. (Horse Racing) Of, pertaining to, or designating, the most heavily weighted race in a meeting; as, a welter race; the welter stakes. [1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Welter \Wel"ter\, n. [1913 Webster] 1. That in which any person or thing welters, or wallows; filth; mire; slough. [1913 Webster]
The foul welter of our so-called religious or other controversies. --Carlyle. [1913 Webster]
2. A rising or falling, as of waves; as, the welter of the billows; the welter of a tempest. [1913 Webster]