A plait is a knot usually tied from multiple lines and exhibiting a repeating pattern, often a braid and often referring to hair. Plait is also a verb used for the act of creating a plait.
For example:
...Bess, the landlord's daughter, plaiting a dark red love-knot into her long black hair.
The Polish plait is typically a (sometimes large) head of hair, made of a hard impenetrable mass of keratin fibers permanently cemented together with dried pus, blood, old lice egg-casings and dirt.
A growing plait was supposed to take the illness "out" of the body, and therefore it was rarely cut off; in addition, the belief that a cut-off plait could avenge itself and bring an even greater illness discouraged some from attacking it.
Plaits were even categorized in a quite sophisticated way; there were plaits "male" and "female", "inner" and "outer", "noble" and "fake", "proper" and "parasitical".