1That remains fixed in a particular place or position; that clings or holds fast. Now rare except in "stickfast flea".
2Of a substance or its properties: that binds or adheres strongly; very sticky.
3Designating a person who remains stubbornly or unwaveringly attached to a course of action or way of life; characteristic of such a person; steadfast.
Early 17th century (in an earlier sense). From stick + fast.