148.130.  Definition of terms. — For the purposes of this law, the following terms shall have the following meanings:

  (1)  The term "director of finance" means the chief officer of the present state division of finance, or of such agency of the state of Missouri as may hereafter have by law the supervisory duties of the present state division of finance pertaining to credit institutions of this state.

  (2)  The term "credit institution" means every person, firm, partnership, or corporation engaged principally in the consumer credit or loan business in the making of loans of money, credit, goods, or things in action, or in the buying, selling, or discounting of, or investing in negotiable or nonnegotiable instruments given as security for or in payment of the purchase price of consumer goods.  Without limiting the generality of the foregoing, the term "credit institution" shall include persons, firms, partnerships, and corporations, operating or licensed under the small loan laws of this state, or under the laws of this state relating to loan and investment companies, and pawnbrokers, but shall not include banks, trust companies, credit unions, insurance companies, mutual savings and loan associations, savings and loan associations, or real estate mortgage loan companies.

  (3)  The term "director" means the director of revenue in charge of the state department of revenue.

  (4)  The term "income period" means the calendar year or relevant portion thereof next preceding the taxable year.

  (5)  The term "taxable year" means the calendar year in which the tax is payable.

  (6)  The term "taxpayer" means any credit institution subject to any tax imposed by sections 148.120 to 148.230.