"mud," 1824, from Irish and Gaelic clabar "mud." Also often short for bonnyclabber. As a verb, "become thick" (of milk, etc.), by 1880.
Entries linking to clabber
bonnyclabber n.
also bonny-clabber, "clotted or coagulated soured milk," 1620s (in shortened form clabber), from Modern Irish bainne "milk" (from Middle Irish banne "drop," also, rarely, "milk"; cognate with Sanskrit bindu- "drop") + claba "thick." Compare Irish and Gaelic clabar "mud," which sometimes has made its way into English (Yeats, etc.).