The Collaborative International Dictionary of English v.0.48:

Bonnyclabber \Bon"ny*clab`ber\ (-kl[a^]b`b[~e]r), n. [Ir.
   bainne, baine, milk + clabar mud, mire.]
   Coagulated sour milk; loppered milk; curdled milk; --
   sometimes called simply clabber. --B. Jonson.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Clabber \Clab"ber\, n. [See Bonnyclabber]
   Milk curdled so as to become thick.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Clabber \Clab"ber\, v. i.
   To become clabber; to lopper.
   [1913 Webster]

WordNet (r) 3.0 (2006):

clabber
    n 1: raw milk that has soured and thickened
    v 1: turn into curds; "curdled milk" [syn: curdle, clabber,
         clot] [ant: homogenise, homogenize]