Whilk is sometimes used in Chaucer to represent the Northern dialect.
Whi"lom (hw"lm), adv. [AS. hwlum, properly, at times, dative pl. of
hwl; akin to G. weiland formerly, OHG. hwlm, See While, n.] Formerly;
once; of old; erewhile; at times. [Obs. or Poetic] Spenser.
Whilom, as olde stories tellen us, There was a duke that highte
Theseus.
Chaucer.