A lock combination is a set of numbers or symbols used to open a lock. It is often used to secure items such as safes, luggage, and other valuables. The crossword solutions for the term 'lock combination' are COIF (4 letters), PLAIT (5 letters), and HAIRDO (6 letters). A COIF is a close-fitting cap worn by medieval knights, while a PLAIT is a type of braid or interweaving of strands of hair. A HAIRDO is a style of arranging the hair, usually with the use of styling products.