Wiktionary
vb. (context transitive obsolete Northern England Scotland English) to make cloth (especially tweed in Scotland) denser and more felt-like by soaking and beating
Usage examples of "waulk".
A strange silence hung over the land, though houses stood undamaged, serene and peaceful, no smoke rose from the chimneys, no sound of horses stamping, children playing, hammers beating on anvils or the work-songs of women weaving or waulking their cloth.
Alone among the Highland farms, I was sure, the women of Lallybroch waulked their wool not only to the old traditional chants but also to the rhythms of Molière and Piron.
And smell aside, the waulking shed was a warm, cozy place, where the women of Lallybroch visited and joked between bolts of cloth, and sang together in the working, hands moving rhythmically across a table, or bare feet sinking deep into the steaming fabric as we sat on the floor, thrusting against a partner thrusting back.