Webster's Revised Unabridged Dictionary · 1913

Whilk

Whilk , noun

[See Whelk a mollusk.]

1.
(Zoology) A kind of mollusk, a whelk. [Provincial English]
2.
(Zoology) The scoter. [Provincial English]

Whilk , pronoun

Which. [Obsolete or Scottish]

Whilk is sometimes used in Chaucer to represent the Northern dialect.