To cheat, to obtain goods and decamp without paying for them.
“The landlord explained it by saying that ‘a bilkʹ is a man who never misses a meal and never pays a cent.”—A. K. McClure: Rocky Mountains letter xxii. p. 211.
⁂ To “bilk” in cribbage is to spoil your adversariesʹ score; to balk him. Perhaps the twowords are mere variants.