The term 'MECHANIC's ___' can be filled in with two four-letter words: LIEN and olan. A LIEN is a legal claim or right on a property by a creditor, such as a MECHANIC who has not been paid for their services. An olan is a type of LIEN that is used to secure payment for labor or materials used in the construction of a building. Both liens and olan are important tools for mechanics to ensure they are paid for their work.